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以下内容来自译自《iPad User Experience Guidelines》，由戴传庆翻译完成，戴传庆校对。 版权声明：文章英文原版版权归原作者所有，译文版权归原作者和求是设计会共同拥有。译文首发于戴传庆个人博客，转载时请以超链接形式标明文章原始出处和作者信息。

Content and interactivity are paramount in the iPad user experience. The best iPad applications elevate content and interactivity by doing three things really well:

iPad用户体验最主要体现在内容和交互：

• They downplay application UI so that the focus is on the content that people want.
• 淡化程序UI，以便用户关注所需的内容。
• They present the content in beautiful, often realistic ways.
• 美观的内容形式，富有真实感。
• They take full advantage of device capabilities to enable enhanced interaction with the content.
• 充分利用设备的性能来增强内容的交互性。

The primacy of content and interactivity inform the guidelines in this chapter. Keep this in mind as you design your iPad application.

在开发你自己的iPad应用时，请谨记这篇守则中提到的关于内容和交互性的一切。

Aim to Support All Orientations 支持所有方位

Being able to run in all orientations is an important factor in the success of your iPad application. The large screen mitigates people’s desire to rotate the device to landscape to “see more.” And, because people don’t pay much attention to the minimal device frame or the location of the Home button, they don’t view the device as having a default orientation. This leads people to expect applications to run well in the device orientation they’re currently using. As much as possible, your application should encourage people to interact with iPad from any side by providing a great experience in all orientations.

The difference between landscape and portrait dimensions can significantly affect how your UI fits onscreen. Precisely how you respond to rotation might vary, but you should make every effort to abide by the following guidelines.

优秀iPad程序的其中一个重要因素是可以在所有方位上运行。竖向的大屏幕可以满足用户浏览内容的需求（当竖屏幕较小时，用户就会将屏幕旋转为横屏幕，这样一行就可以显示较多的文字）。用户不太会注意最小设备结构（minimaldevice frame；使用iPhone时，用户单手握住手机时，屏幕多为竖向显示；而双手使用iPad，屏幕的显示方位并不能确定）或者home按键的位置，他们不认为设备有默认方位。这就导致用户期望程序可以在当前方位上运行。所以程序尽量满足iPad各方位的运行要求。

Maintain focus on the primary content. This is your highest priority. People use your application to view and interact with the content they care about. Altering the focus on that content in different orientations can make people feel that they’ve lost control over the application.

保证以首要内容为重点。当旋转iPad的方位时，如重点显示的内容发生变化，用户会感觉对程序失去控制。

Consider changing how you display auxiliary information or functionality. Although you should make sure that the most important content is always in focus, you can respond to rotation by changing how you provide secondary content.

旋转时如何显示辅助信息或者功能。尽管能保证上一条，还要考虑如何显示较为次要的信息。

In Mail, for example, the lists of accounts and mailboxes comprise secondary content (the main content is the selected message). In landscape, secondary content is displayed in the left pane of a split view; in portrait, it’s displayed in a popover.

例如邮箱功能中，首要内容时发邮件，次要内容是联系人和收件箱的列表。

横屏的次要内容显示在左边的分视图中

竖屏的次要内容显示在气泡框中。

Or, consider a game that displays a rectangular game board in landscape. In portrait, the game needs to redraw the board to fit well on the screen, which might result in additional space above or below the board. Instead of vertically stretching the game board to fit the space or leaving the space empty, the game could display supplemental information or objects in the additional space. Both of these examples maintain the user’s focus on the primary content and take best advantage of the current screen dimensions without altering the primary functionality of the application.

再如，横屏时，一款游戏以长方形显示，当旋转到竖屏时，需要调整屏幕上的显示区域，游戏显示边框的上面或者下面增加显示空间，用于显示辅助信息，而不是垂直拉伸显示区域来撑满整个屏幕。

Avoid radical or gratuitous changes in layout. The large iPad screen allows you to provide a similar UI layout in all orientations. For example, if you display images in a grid while in landscape, you don’t need to display the same information in a list while in portrait (although you might adjust the dimensions of the grid). Focus on providing a consistent experience in all orientations, even if the layout of secondary information might change. A comparable experience in all orientations allows people to maintain their usage patterns when they rotate the device.

When possible, avoid reformatting information and rewrapping text on rotation. Strive to maintain a similar format in all orientations. Especially if people are reading text, it’s important to avoid causing them to lose their place when they rotate the device.

避免布局变化过大或者无缘由地改变。所有方位中都显示相似的UI布局旋转时尽可能保留信息和文本的原有格式。尤其阅读文本时，重要的是避免旋转之后用户找不到读到哪儿了。如果非要对页面重新布局，可以使用动画帮助用户理解当前页面的变化。例如，当旋转时要必须增加或者移除文本框时，可以选择隐藏动作并在新布局中简单地淡出。为了有助于合理地设计旋转动作，可考虑在真实的生活中是如何和它们交互的。

Avoid providing a UI element or defining a rotation gesture that rotates your content. Instead, people should be able to rotate your content by rotating the device.

避免使用UI元素或者定义一个旋转的手势来完成旋转动作。应该是内容随着iPad的旋转而旋转。

Provide a unique launch image for each orientation. When each orientation has a unique launch image, people experience a smooth application start regardless of the current device orientation. In contrast with the Home screen on iPhone, the iPad Home screen supports all orientations, so people are likely to start your application in the same orientation in which they quit the previous application. See “Create a Launch Image for Each Orientation” for more information on iPad launch images.

为每个显示方位各提供一个启动图片。比如提供1004×768和748×1024的图片来满足两个方位的显示要求。

Think twice before preventing your application from running in all orientations. People expect to use your application in whichever orientation they’re currently holding their iPad, and it’s best when you can fulfill that expectation. In certain cases, however, an application needs to run in portrait only or in landscape only. If it’s essential that your application run in only one orientation, you should:

仔细考虑程序是否可以在所有方位上运行。有些程序只能在横屏或者竖屏下显示，此时：

• Launch in your supported orientation, regardless of the current device orientation. For example, if your game or media-viewing application runs in landscape only, it’s appropriate to launch in landscape, even if the device is currently in portrait. This way, if people start your application in portrait, they know to rotate the device to landscape to view the content.
• 显示程序为正常显示方式，无论当前iPad是什么方位。
• Avoid displaying a UI element that tells people to rotate the device. Launching in your supported orientation clearly tells people to rotate the device, if required, without adding unnecessary clutter to your UI.
• 避免使用UI元素来告知用户旋转设备。
• Support both variants of an orientation. For example, if your application runs only in landscape, people should be able to use it whether they’re holding the device with the Home button on the right or on the left. And, if people rotate the device 180 degrees while using your application, it’s best if you can respond by rotating your content 180 degrees.
• 支持180度旋转。

If your application interprets changes in device orientation as user input, you can handle rotation in application-specific ways. For example, if your application is a game that allows people to move game pieces by rotating the device, you can’t respond to device rotation by rotating the screen. In a case like this, you should launch in either variant of your required orientation and allow people to switch between the variants until they start the main task of the application. Then, as soon as people begin the main task, you can begin responding to device movement in application-specific ways.

可以特殊处理输入式旋转动作。有些游戏把旋转设备当成操作方式，这时候横竖屏切换时，可不改变游戏的显示方位。

Enhance Interactivity (Don’t Just Add Features) 增强交互

The best iPad applications give people innovative ways to interact with content while they perform a clearly defined, finite task. Resist the temptation to fill the large screen with features that are not directly related to the main task. In particular, you should not view the large iPad screen as an invitation to bring back all the functionality you pruned from your iPhone application.

最好的iPad程序在用户执行明确的任务时提供新颖的交互方式。不要为了填满整个大屏幕而增加一些和主要任务没有直接关联的功能，而是提升程序的用户体验。

To make your iPad application stand out, concentrate on ways to amplify the user experience, without diluting the main task with extraneous features. For example:

• A book-reader application that allows people to read books and keep track of reading lists can provide a much more enjoyable reading experience on the large screen. Instead of making people transition to another screen to manage their reading lists, the application can put the list in a popover and allow people to copy favorite passages into it. The application can also let people add bookmarks and annotations to the text, and help them trade their lists with others or compare their progress against a central repository of lists.
• A fighter pilot game might enable a translucent heads-up display over the main view. Players can tap realistic cockpit controls to engage the enemy or locate themselves on a map overlay.
• A soccer playing game can display a larger, more realistic playing field and more detailed characters, and allow people to manage their teams and customize the characters. It can also allow people to see information about characters without leaving the field view. Finally, it can enable a multiplayer mode in which two people can pit their teams against each other.
• A screen writing application might provide ways to switch between a plot view and a character view without leaving the main context. Writers can switch between these views to check details as they write in the main view.

例如读书程序中容许用户阅读时如能保留路径会提升阅读体验，不需要跳转到另外一个页面而是使用气泡框来变更路径。程序可以让用户在文本中增加书签和注释，帮助用户交换书目或者对比阅读进度。

Flatten Your Information Hierarchy 信息扁平化

Use the large iPad screen and new UI elements to give people access to more information in one place. Although you don’t want to pack too much information into one screen, you also want to prevent people from feeling that they must visit many different screens to find what they want.

In general, focus the main screen on the primary content and provide additional information or tools in an auxiliary view, such as a popover. This gives people easy access to the functionality they need, without requiring them to leave the context of the main task.

With the large iPad screen, and UI elements such as split view and popover, you have alternatives to the one-level-per-screen structure of many iPhone applications. For example, you can:

iPad的大屏幕和新UI元素可以显示更多的信息，使用的得当可以避免寻找信息时跳转的次数过多,因此也改变iPhone的单屏显示结构。例如：

Use a navigation bar in the right pane of a split view to allow people to drill down into a top-level category that is persistently displayed in the left pane. This flattens your information hierarchy by at least one level, because two levels are always onscreen at the same time. Settings displays device and application settings in this way, as shown in Figure 3-1. (See “Split View” for usage guidelines.)

Use a navigation bar in the left pane of a split view to allow people to drill down through a fairly shallow hierarchy. Then, display the most specific information (that is, the leaf nodes in the hierarchy) in the right pane. This, too, flattens your hierarchy by displaying two levels onscreen at one time. Mail in landscape uses this design to display the user’s mailbox hierarchy in the left pane, as shown in Figure 3-2; individual messages are displayed in the right pane, as shown in Figure 2-2. (See “Navigation Bar” for usage guidelines.)

使用分栏。两级的内容同时显示使得信息扁平化。

Use a popover to enable actions or provide tools that affect onscreen objects. A popover can display these actions and tools temporarily on top of the current screen, which means people don’t have to transition to another screen to get them. Mail in portrait uses a popover to display the user’s account and mailbox hierarchy, as shown in Figure 3-3. (See “Popover”for usage guidelines.)

使用气泡框。顶部的气泡框可以显示控件或者工具，不必切换屏幕即可完成操作。

Use a segmented control in a toolbar to display different perspectives on the content or different information categories. In this way, you can provide access to these perspectives or categories from a single bar at the top (or the bottom) of the screen. iTunes uses a segmented control in a top-edge toolbar to provide different perspectives on the content in a category, as shown in Figure 3-4. (See “Toolbar” and “Segmented Control” for usage guidelines.)

工具栏中显示分段控件。分段控件可以显示并列的信息。

Use a tab bar to display different information categories or, less often, different application modes. In iPad applications, a tab bar is more likely to be used as a filter or category switcher than as a mode switcher. As shown in Figure 3-5, iTunes uses a tab bar to give people access to different categories of media. It’s worth changing your information architecture to avoid multiple, parallel modes, if this allows you to avoid using a tab bar to swap in different screens. (See “Tab Bar” for usage guidelines.)

使用标签栏。标签栏显示不同种类信息或者是不同的程序模块。

Reduce Full-Screen Transitions 减少全屏切换

Closely associate visual transitions with the content that’s changing. Instead of swapping in a whole new screen when some embedded information changes, try to update only the areas of the user interface that need it. As a general rule, prefer transitioning individual views and objects, not the screen. In most cases, flipping the entire screen is not recommended.

When you perform fewer full-screen transitions, your application has greater visual stability, which helps people keep track of where they are in their task. You can use UI elements such as split view and popover to lessen the need for full-screen transitions.

相似的视觉元素，而在某一区域变更内容。普遍的规则是宁愿转换单独的视图或者组件，也不全屏切换，保证视觉稳定性，帮助用户理解自己所处的位置。

Enable Collaboration and Connectedness 增强协作和联系

People view iPad as a personal device, but its convenient size also encourages physical collaboration and sharing with others.

Think of ways people might want to use your application with others. Expand your thinking to include both the physical sharing of a single device and the virtual sharing of data. For example, two people might be able to play a game on opposing sides of an onscreen board. Or a band application might allow different people to play different instruments together on a single device.

People expect to be able to share information that’s important to them. When it makes sense in your application, make it easy for people to interact with others and share things like their location, opinions, and high scores.

Most applications can add value by allowing people to go beyond the application and share data with other tools they use. For example, an iPad application can act as a mobile complement to a computer application. Or, an iPad application might allow its users to communicate with the users of the iPhone version of the application.

用户将iPad视为私人设备，但是它合宜的尺寸可以加强真实的协作和分享。

Add Physicality and Heightened Realism 真实感

Whenever possible, add a realistic, physical dimension to your application. The more true to life your application looks and behaves, the easier it is for people to understand how it works and the more they enjoy using it. For example, people instantly know how to use the realistic address book that Contacts portrays (shown in Figure 3-6).

As you work on adding realistic touches to your application, don’t feel that you must strive for scrupulous accuracy. Often, an amplified or enhanced portrayal of something can seem more real, and convey more meaning, than a faithful likeness. As you design objects and scenes, think of them as opportunities to communicate with your users and to express the essence of your application.

Use animation to further enhance realism in your application. In general, it’s more important to strive for accuracy in movement than in appearance. This is because people accept artistic license in appearance, but they can feel disoriented when they see movement that appears to defy physical laws. As much as possible, make sure your virtual views and controls mimic the behavior of the physical objects and controls they resemble. Convincing animation heightens people’s impression of your application as a tangible, physical realm in which they want to spend time.

程序显示和现实生活越为相似，用户就越容易理解程序如何操作并喜欢使用。但也不必过于精确，通常夸张的事物看起来更为真实并能传递更多的意义，当做是和用户交流并表述程序本质的一次机会。使用动画进一步地增强程序的真实感。通常，动作的真实感比程序的外观更为重要，不符合物理规律的动作会让用户感觉到迷惑。

Delight People with Stunning Graphics 令人惊叹的图形

The high-resolution iPad screen supports rich, beautiful, engaging graphics that draw people into an application and make the simplest task rewarding. iPad showcases your application’s artwork, so you should consider hiring a professional artist to create first-rate graphics that people will admire.

One way to increase the perceived value of your application is to replicate the look of high-quality or precious materials. For example, if the effect of wood, leather, or metal is appropriate in your application, take the time to make sure the material looks realistic and valuable. As shown in Figure 3-7, Notes reproduces the look of fine leather and meticulous stitching.

If your artwork is not already high resolution, you may need to recreate it. In most cases, scaling up your artwork is not recommended as a long-term solution. Instead, try creating your artwork in a dimension that is larger than you need, so you can add depth and details before scaling it down. This works especially well when the dimension of the original art file is a multiple of the dimension you need. Then, if you also use an appropriate grid size in your image-editing application, you’ll be able to keep the scaled-down art file crisp and reduce the amount of retouching and sharpening you need to do.

In addition to updating all your textures, effects, and images, make sure you remove from your code any hard-coded values that identify screen dimensions.

Update your existing launch images and create additional ones, if necessary (see “Create a Launch Image for Each Orientation”).

Create a large application icon (see “Create a Beautiful Application Icon”).

高分辨率的iPad屏幕所支持丰富、美观和动人的图形对用户富有吸引力，因此可以尝试增加程序中图形的深度和细节。

De-emphasize User Interface Controls 弱化界面控件

Help people focus on the content by designing your application UI as a subtle frame for the information they’re interested in. Downplay application controls by minimizing their number and prominence. Photos does this by placing a few unobtrusive controls on translucent bars.

Consider creating custom controls that subtly integrate with your application’s graphical style. In this way, controls are discoverable, without being conspicuous.

Also, consider fading controls after people have stopped interacting with them for a little while, and redisplaying them when people tap the screen. Sometimes you may want to fade the rest of your application UI, too. This gives even more of the screen space to the content people want to see. For example, Photos fades the controls and bars after a few moments of noninteraction, which encourages people to immerse themselves in the content.

通过设计程序中的UI来组织信息框架，减少控件的数量和淡化显示效果，创建和程序风格相符的控件，这样既不突出，但又易于发现。

Minimize Modality 最少的模态对话框

When possible, minimize the number of times people must be in a modal environment to perform a task or supply a response. iPad applications should allow people to interact with them in nonlinear ways. Modality prevents this freedom by interrupting people’s workflow and forcing them to choose a particular path.

Modality is most appropriate when:

模态对话框打断用户的工作流，需用在合适的情况下：

• It’s critical to get the user’s attention.
• 有必要吸引用户注意力的时候。
• A task must be completed (or explicitly abandoned) to avoid leaving the user’s data in an ambiguous state.
• 避免用户因误操作而导致的数据丢失。

Rethink Your Lists 重新思考列表

Lists (that is, table views) are a common way to efficiently display large amounts of information in iPhone applications. Lists are very useful in iPad applications, too, but you should take this opportunity to investigate whether you can present the same information in a richer way. For example:

• Consider a more real-world vision of your application. For example, on iPhone, Contacts is a streamlined list, but on iPad, Contacts is an address book with a beautifully tangible look and feel (this is shown in Figure 3-6).
• Consider presenting some of the information as objects instead of list items. For example, the iPod application displays albums in a grid of album cover thumbnails. And in Mail, messages that people mark for deletion are displayed as a stack of realistic sheets of paper (this is shown in Figure 2-4).
• Constrain the width of a list by embedding it in another view. For example, it might be appropriate to display a list inside a popover or on the flip side of a view instead of in the full width of the screen.
• When possible, avoid displaying list information in precisely the same format as you do in your iPhone application. On iPad, lists are much wider, so content that fills a list row on iPhone can look sparse on iPad. Take advantage of the extra room to provide additional information or details on each row.

列表（也就是表视图）在iPhone中常用于显示大量的数据信息，在iPad也是非常有用。但是还可以使用一个更丰富的方式来显示同样的信息。例如：iPhone中的联系方式是一个很有效率的列表。而在iPad中的联系方式看起来是一个美观的通讯录，iPad的列表可以显示更多的信息。

Consider Multifinger Gestures 多点触摸

The large iPad screen provides great scope for custom multifinger gestures, including gestures made by more than one person. Although complex gestures are not appropriate for every application, they can enrich the experience in applications that people spend a lot of time in, such as games or content-creation environments. Always bear in mind that nonstandard gestures aren’t discoverable and should rarely, if ever, be the only way to perform an action.

Be sure the gestures you use make sense in the context of your application’s functionality and the expectations of your users. If, for example, your application enables an important task that users perform frequently and want to complete quickly, you should probably use only standard gestures. But if your application contains realistic controls that dictate a specific usage, or provides an environment that users expect to explore, custom or multifinger gestures can be appropriate. (For more information about the standard gestures, see “Support Gestures Appropriately” in iPhone Human Interface Guidelines.)

大屏幕支持自定义的多点触摸，即使是多人同时使用iPad，牢记不用响应不标准的触摸手势，如果有的话，也只用一种方式来执行命令。

Consider Popovers for Some Modal Tasks 气泡框

Popovers and modal views are similar, in the sense that people typically can’t interact with the main view while a popover or modal view is open. But a modal view is always modal, whereas a popover can be used in two different ways:

气泡框和模态视图有些相似，当气泡框显示时，不能操作主视图。但模态视图是模态的。然而气泡框可以用在两种途径：

• Modal, in which case the popover dims the screen area around it and requires an explicit dismissal. This behavior is very similar to that of a modal view, but a popover’s appearance tends to give the experience a lighter weight.
• 模态。气泡框出现时，周围的界面淡化，需要一个明确的操作取消。
• Nonmodal, in which case the popover does not dim the screen area around it and people can tap outside its bounds to dismiss it. This behavior makes a nonmodal popover seem like another view in the application, not a separate state.
• 非模态。点击气泡框周围的界面也可以取消气泡框。

In addition, a popover always has an arrow that points to the control or area the user tapped to reveal it. This visual tie-in helps people remember their previous context. It also makes a modal popover seem like a more transient state than a modal view, which takes over the screen without indicating where it came from.

If you use modal views to enable self-contained tasks in your iPhone application, you might be able to use popovers instead. To help you decide when this might be appropriate, consider these questions:

如果在iPhone中使用了模态视图，可以考虑可以气泡框替代它。以下问题可以帮助你决定气泡框的使用是否合理：

• Does the task require different types of input? If so, use a popover.

  Although a keyboard can accompany either a popover or a modal view, a popover is better for displaying a picker or a list of options.

• 是否需要不同类型的输入？如果是，使用气泡框。气泡框更适合显示一个选择器或者列表选项。

• Does the task require people to drill down through a hierarchy of views? If so, use a popover.

  The frame of a popover is better suited to displaying multiple pages, because there is less chance people will confuse it with the main view.

• 是否需要用户穿过多级视图。如果是，使用气泡框。气泡框的结果适合显示多级页面，因为对主视图的改变较小。

• Might people want to do something in the main view before they finish the task? If so, use a nonmodal popover.

  Because people can see the main view around a nonmodal popover and they can dismiss it by tapping in the main view, you should allow them to suspend the popover’s task and come right back to it.

• 可能在主视图操作才可以完成任务吗？如果是，使用非模态气泡框。因为用户点击主视图即可取消气泡框，容许用户中止操作气泡框并返回主视图。

• Is the task fairly in-depth and does it represent one of the application’s main functions? If so, you might want to use a modal view.

  The greater context shift of a modal view helps people stay focused on the task until they finish it. The greater screen space of most modal view styles makes it easier for people to provide a lot of input.

  If, on the other hand, the task represents an important part of application functionality, but it is not in-depth, a modal popover can be a better choice. This is because the lighter visual weight of a popover can be more pleasant for frequently performed tasks.

• 任务需要用户深度投入并且是程序的一个主要功能？如果是，可能需要使用模态视图。模态视图的语境转换帮助用户在任务上集中注意力，较大模态视图便于用户输入大量的字符段。

  从另一方面而言，这个任务代表程序功能的重要一部分，但要是不需要用户深度投入注意力的话，气泡框是更好的选择，轻量级的视觉对于频繁执行的任务而言更为亲切。

• Is the task performed only once or very infrequently, as with a setup task? If so, consider using a modal view.

  People aren’t as concerned about staying in the current context when they perform a task only once or very infrequently.

• 是否任务执行只有一次或者很少，就像安装任务。如果是，考虑使用模态视图。用户不会介意为了完成此类任务而停留在当前界面。

There are a number of other uses for popovers, such as to provide auxiliary tools (for complete usage guidelines, see “Popover”). Also, be aware that iPad applications display action sheets inside popovers (for more information, see “Action Sheet”).

If you decide to use a modal view, be sure to read about the different presentation styles you can use (they’re described in “Modal View”). In your iPad application, you can choose the presentation style that’s best suited to the modal task you need to enable.

Restrict Complexity in Modal Tasks 限制模态任务的复杂度

People appreciate being able to accomplish a self-contained subtask in a modal view, because the context shift is clear and temporary. But if the subtask is too complex, people can lose sight of the main task they suspended when they entered the modal view. This risk increases when the modal view is full screen and when it includes multiple subordinate views or states.

Try to keep modal tasks fairly short and narrowly focused. You don’t want your users to experience a modal view as a mini application within your application. Be especially wary of creating a modal task that involves a hierarchy of modal views, because people can get lost and forget how to retrace their steps. If a modal task must contain subviews, be sure to give users a single, clear path through the hierarchy, and avoid circularities.

Always provide an obvious and safe way to exit a modal task. People should always be able to predict the fate of their work when they dismiss a modal view or popover.

If the task needs multiple modal views, make sure your users understand what happens if they tap a Done button on a view that’s below the top level. Examine the task to decide whether a Done button in a subview should finish only that subview’s part of the task or the entire task. When possible, avoid adding Done buttons to subviews, because of this potential for confusion.

用户乐于在一个模态视图中完成一个子任务，因为语境的转换清晰和短暂的。但是如果子任务太复杂，用户会忽视主任务，当模态视图全屏显示并包含多个子视图时，这种危险会增加。如果模态任务非要包含子视图，确保给予用户一个单独和层次清晰的路径，避免迂回。提供一个明显和安全的方式退出模态任务，用户能预见此操作的后果。

Downplay File-Handling Operations 淡化文件管理

Although iPad applications can allow people to create and manipulate files, this does not mean that people should have a sense of the file system on iPad.

On iPad, there is no application analogous to the Mac OS X Finder, and people should not be asked to interact with files as they do on a computer. In particular, people should not be faced with anything that encourages them to think about file types or locations, such as:

尽管iPad程序容许用户创建和操作文件，这并不意味着用户应该对于文件系统有意识。iPad没有像Mac OS一样的文件搜索，用户也不必想在电脑上一样和文件进行交互。用户不应该考虑文件类型和位置，比如：

• An open or save dialog that exposes a file hierarchy
• 打开和保存对话框中出现文件层级关系。
• Information about the permissions status of files
• 文件的访问权限信息。

Instead, a document-handling iPad application should encourage people to view their content as objects in the application.

If your iPad application allows people to create and edit documents, it’s appropriate to provide some sort of document picker that allows them to open an existing document or create a new one. Ideally, such a document picker:

一个文件处理程序鼓励用户预览内容。如果iPad程序容许用户创建和编辑文档，最好提供文档种类选择器便于用户打开一个现有文档或者创建新文档。理想情况下的文档选择器为：

• Is highly graphical. People should be able to easily identify the document they want by looking at visual representations of the documents onscreen.
• 高度图形化。用户看到文档的视觉形式时能很容易识别出需要的文档。
• Allows people to make the fewest possible gestures to do what they want. For example, people might scroll horizontally through a carousel of existing documents and open the desired one with a tap.
• 用户使用最少的触摸手势找到需要的内容。例如打开一个文档只需平移水平滚动条和轻击文档。
• Includes a new document function. Instead of making people go somewhere else to create a new document, a document picker can allow them to tap a placeholder image to create a new document.
• 创建新文档的功能。当用户没有找到想要的文档时，选择器提供一个创建文档的功能而不是到其他界面寻找此功能。

Ask People to Save Only When Necessary 只有需要的时候才要求用户保存

People should have confidence that their work is always preserved unless they explicitly cancel or delete it. If your application helps people create and edit documents, make sure they do not have to take an explicit save action. iPad applications should take responsibility for saving people’s input, both periodically and when they open a different document or quit the application.

If the main function of your application is not content creation, but you allow people to switch between viewing information and editing it, it can make sense to ask them to save their changes. In this scenario, it often works well to provide an Edit button in the view that displays the information. When people tap the Edit button, you can change it to a Save button and add a Cancel button. The transformation of the Edit button helps remind people that they’re in an editing mode, and the Cancel button gives them the opportunity to exit without saving their changes.

In general, save information that people enter in a popover (unless they cancel their work), because they might dismiss the popover without meaning to. For more guidelines specific to using popovers, see “Popover.”

用户应该确信他们的工作是实时地被保存，除非他们明确取消或者删除。如果程序帮助用户创建和编辑文档，保证用户不需要明确地执行保存命令。如果程序的主要功能不是创建内容，但要容许用户切换浏览和编辑模式，这时可以明确要求用户保存修改内容。在这种情况下，信息显示的视图中提供“编辑”按钮，轻击之后，该按钮变为“保存”按钮和“取消”按钮。“编辑”按钮的转换提醒用户当前界面为编辑模式，“删除”按钮让用户不保存修改内容的情况下退出程序。

Migrate Toolbar Content to the Top 工具栏移至顶部

If your iPhone application has a toolbar, consider moving it to the top of the screen instead of leaving it at the bottom. With the additional width of the iPad screen, you should be able to provide all of your toolbar functionality in a single toolbar at the top. This gives you more vertical space for your focused content.

For example, Mail on iPhone uses a toolbar to give people access to the refresh, organize, trash, reply, and compose actions while they view messages, as shown in Figure 3-8.

Mail on iPad provides access to all but one of these actions in the toolbar above the message, as shown in Figure 3-9. The Refresh control is in the mailbox list, which is in a popover in portrait and in the left pane of the split view in landscape.

与iPhone程序不同，iPad的工具栏在顶部，iPad宽大屏幕可以显示工具栏中的所有功能。

Start Instantly 立即启动

iPad applications should start as quickly as possible so that people can begin using them without delay. When starting, iPad applications should:

iPad程序启动时用户无须等待即可开始操作。当启动时，iPad程序：

• Display a launch image that closely resembles the first application screen in the current orientation. This decreases the perceived launch time of your application and helps to reassure people that the device is active. (For more information, see “Create a Launch Image for Each Orientation.”)
• 显示程序在当前方位上的启动图片，减轻用户的等待感，让用户知道程序仍在运行。
• Avoid displaying an About window or a splash screen that slows application startup. You’re not prohibited from displaying information about your brand, but you need to remember that your users will see this content every time they start your application. If you feel you must display a splash screen, make sure that it doesn’t remain visible for too long and that it disappears without requiring any user interaction. Your main concern should be to make your application launch quick and pleasant.
• 避免程序启动变慢。启动图片（launch image)中显示品牌信息是容许的，但是铭记用户启动程序时每次都会看到这个内容。如果非要使用启动画面（splash screen），明确显示时候不是过长并且无需任何用户交互。
• Restore state from the last time the application ran. People should not have to remember the steps they took to reach their previous location in your application.
• 恢复程序上一次运行状况。
• Avoid asking people to supply setup information. Instead, you should:

• 避免要求用户提供启动信息。取而代之的是：

  • Focus your solution on the needs of 80 percent of your users. When you do this, most people do not need to supply settings because your application is already set up to behave the way they expect. If there is functionality that only a few people might want, or that most people might want only once, leave it out.
  • 关注80%的用户需求。
  • Get as much information as possible from the system. If you can use any of the information people supply in built-in application or device settings, query the system for these values; don’t ask people to enter them again.
  • 从系统中获取更多的信息。从系统中调取信息可以避免输入。
  • Let people benefit from your application before prompting them for input. If you must get information from people before they can use all the features of your application, first help them accomplish something that doesn’t require their input. Later, ask for information when it’s necessary, and store it as soon as possible so that you don’t have to ask for it again.
  • 用户在输入前受益。如果输入不可避免，那也要在用户先让获取有效信息。

Always Be Prepared to Stop 随时准备停止

Like iPhone applications, iPad applications stop when people press the Home button to open another application. Therefore, to provide a good stopping experience, an iPad application should:

和iPhone一样，iPad程序在用户按“Home”键之后，因此：

• Save user data as soon as possible and as often as reasonable, because an exit or terminate notification can arrive at any time. When you save frequently, your application quits more quickly and people don’t have to tap a Save button (see “Ask People to Save Only When Necessary”).
• 尽快和合理地保存数据。
• Save the current state when stopping, at the finest level of detail possible. People expect to return to their earlier context when they restart your application. For example, if you use a split view, remember the current selection in the master pane and display it when the user starts your application again.
• 退出时保存界面的每一个细节。