Modality creates focus by preventing people from doing other things until they complete a task or dismiss不予理会 a message or view. Action sheets, alerts, and activity views provide modal experiences. When a modal view appears onscreen, the user must make a choice by tapping a button or otherwise否则 exiting the modal experience. Some apps implement实施 modal views, such as while editing an event in Calendar or choosing a bookmark标记 in Safari. A modal view can occupy占据 the entire screen, an entire parent view, such as a popover, or a portion部分 of the screen. A modal view typically代表性的 includes completion and cancel buttons that exit the view.
情态通过防止人们做其它事情（直到他们完成一个任务或者关闭对话、窗口）来创造焦点。动作表、警告和活动视图提供了情态的体验。当一个情态视图在屏幕上出现，用户必须通过点击按钮做出选择或者退出情态体验。一些app在编辑日历中的事件或者选择Safari中的标签等情景时使用情态视图。一个情态视图可以占据整个屏幕、父视图例如一个弹窗或者屏幕的一部分。一个情态视图通常包含完成和取消按钮来退出视图。
Minimize最小化 the use of modality. Generally, people prefer to interact with apps in nonlinear ways. Consider creating a modal context环境、上下文 only when it’s critical临界的 to get someone’s attention, when a task must be completed or abandoned抛弃 to continue using the app, or to save important data.
最小化情态。一般来说人们偏向和app进行非线性的交互。只有当迫不得已的时候才考虑使用情态环境来获得用户的注意力，比如必须要完成或者放弃一个任务才能继续使用app或者保存重要的数据时。
Provide an obvious and safe way to exit a modal task. Make sure people always know the outcome结果 of their action when they dismiss a modal view.
提供一个明显且安全的方法来退出情态任务。确保人们知道他们离开一个情态视图会出现什么结果。
Keep modal tasks simple, short, and narrowly focused. Don’t create an app within your app. If a modal task is too complex, people can lose sight of the task they suspended悬浮、暂停 when they entered the modal context. Be especially wary谨慎 of creating modal tasks that involve a hierarchy层级 of views because users can get lost and forget how to retrace折回 their steps. If a modal task must contain subviews, provide a single path through the hierarchy and a clear path to completion. Avoid using Done buttons for things other than completing the task.
保持情态任务简洁、简短并且重点突出。别在你的app里创建一个app。如果一个情态任务太复杂，人们在进后时会忘记他们之前的事情。创建涉及视图层级的情态任务时要特别谨慎，因为用户可能会迷失并忘记回去的步骤。如果一个情态任务必须包含子视图，提供一个简单的路径来通过层级以及一个清晰的路径来完成。避免在除了完成任务之外其它的情景中使用完成按钮。
Display a title that identifies a task, if appropriate. You might also provide text in other portions部分 of the view that more fully describes the task or provides guidance.
如果合适，使用一个能够识别任务的标题。你也可以在视图中的其它部分提供文本来更加全面的描述任务或提供指导。
Reserve保留 alerts for delivering essential—and ideally理想的 actionable—information. An alert interrupts the experience and requires a tap to dismiss, so it’s important for people to feel that the intrusion is warranted必要的.
为传递重要信息或理想的动作保留警告。一个警告会打断体验并且需要点击才能消失，所以这个警告需要让人们觉的它的存在足够重要。
Respect notification preferences选择权. In Settings, people specify规定 how they want to receive notifications from your app. Abide遵守 by these preferences so they aren’t tempted to turn off your app’s notifications entirely.
忍受通知的选择权。在设置中心，人们可以规定怎样从你的app中收到通知。遵守这些规定使用户不必想要把你的app的通知整个的关掉。
Don’t display a modal view above a popover（弹出框）. With the possible exception of an alert, nothing should appear over a popover. In rare cases when you need to present a modal view after action is taken in a popover, close the popover before displaying the modal view.
不要在一个弹出框上显示情态视图。一个很少存在例外的警告，没有东西可以出现在弹窗上面。只有极少数的情况下，当你需要在一个弹窗上的动作完成后显示情态视图，先关闭弹窗然后再展示情态视图。
Coordinate调整 modal view appearance外观 with your app. A modal view may include a navigation bar, for example. When this is the case, use the same appearance as the navigation bar in your app.
跟随你的app来调整情态视图的外观。例如，一个情态视图可能包含导航条，在这种情况下，使用和你app同样的导航条外观。
Choose an appropriate modal view style. You can use any of these styles:
选择一个情态视图的外观风格。你可以使用下面这些风格。
full screen 覆盖整个屏幕。用在一个可能非常复杂的任务，能够在情态视图中完成。page sheet 在更大的设备的水平视图中，部分的覆盖下面的内容。所有的未覆盖区域变暗以防止和它们相互作用。在较小的设备的纵向视图中覆盖整个屏幕，在一个情态视图中完成复杂任务时使用。
form sheet 出现在屏幕的中间但是当键盘出现的时候回重新定位。左右的未覆盖区域变暗以防止和它们相互作用。在更小的设备上可能会覆盖整个屏幕。用来收集信息。current context 和它的父视图有一样的尺寸。用来展示拆分视图窗格、弹窗、和其它没有铺满屏幕的情态视图
Choose an appropriate合适的 transition过渡 style for revealing展现 a modal view. Use a transition style that coordinates使协调 with your app and enhances提高 the awareness意识 of the temporary临时的 context shift转变. The default transition vertically垂直的 slides the modal view up from the bottom of the screen and back down once dismissed. The flip-style transition appears to flip a view horizontally to reveal显示 the modal view. Visually, the modal view looks like the back of the current view. It flips back once dismissed. Use consistent一致的 modal transition styles throughout your app.
选择一个合适的过渡效果来展现情态视图。使用一种和你的app协调的过渡效果，提高界面转换的效果。默认的过渡效果是从屏幕的下方垂直向上滑出情态视图然后在消失的时候原路返回。弹出风格的过渡是水平的弹出一个情态视图。视觉上情态视图看起来像在当前视图的后面。在消失的时候弹回。在你整个app中使用统一的情态过渡风格。
