出自UXGuide.net

标签栏

Tab Bars

If your application provides different perspectives on the same set of data, or different subtasks related to the overall function of the application, you might want to use a tab bar. A tab bar appears at the bottom edge of the screen.

如果你的应用程序为相同的数据设定提供不同的透视，或者与应用程序所有功能相关联的子功能，你可能需要用到标签栏。标签栏出现在屏幕的底部边缘。

A tab bar gives users the ability to switch among different modes or views in an application, and users should be able to access these modes from everywhere in the application. However, a tab bar should never be used as a toolbar, which contains buttons that act on elements in the current mode (see “Toolbars” for more information on toolbars).

标签栏让用户能够在应用程序中的不同模式或视图中切换，并且用户应该可以在应用程序的任何位置进入到这些模式中。然而，标签栏绝对不应该被当做工具栏（包含控制当前模式中元素按钮）使用。（有关工具栏的更多信息请参见“工具栏”）

For example, on iPhone, iPod uses a tab bar to allow users to choose which part of their media collection to focus on, such as Podcasts, artists, videos, or playlists. The Clock application, on the other hand, uses a tab bar to give users access to the four functions of the application, namely, World Clock, Alarm, Stopwatch, and Timer. Figure 6-10 shows how selecting a tab in a tab bar changes the view in Clock. Notice how the tab bar remains visible in the different Clock modes shown in Figure 6-10. This makes it easy for users to see which mode they’re in, and allows them to access all Clock modes regardless of the current mode.

例如，iPhone和iPod使用标签栏让用户选择将重点放在他们媒体收集的哪个部分，如播客，艺术家，视频或播放列表。另一方面，在时钟程序中，标签栏让用户得以进入到四大功能，即世界时钟，闹钟，秒表和定时器。图6-10展示了如何在标签栏中选择一个标签来改变时钟的视图。注意在图6-10中不同时钟模式中标签栏是如何显示的。用户可以轻而易举的知道他们在哪个模式，并且不管当前是在哪个模式下都允许用户进入到所有其他模式。

Figure 6-10  A tab bar switches views in an application
图6-10 在应用程序中使用标签栏切换视图

The tab bar displays icons and text in tabs, all of which are equal in width and display a black background. When a tab is selected, its background lightens and the image in the tab is highlighted. Figure 6-11 shows how this looks.

所有标签栏显示图标和文字的标签都是相同的宽度并且显示黑色背景。当标签被选中后，它的背景淡化并且标签中的图片变亮。图6-11显示出了它们的样子。

Figure 6-11  A selected tab in a tab bar
图6-11 标签栏中一个被选中的标签

iPhone OS provides a number of icons for tabs, such as the items labeled Featured and Bookmarks in Figure 6-11. If you choose to use these icons, be sure to use them in accordance with their documented meaning. For more information on the tab bar icons available to you, see “Standard Icons for Use in Tab Bars.”

提供额外的标签

Providing Additional Tabs

If your application's tab bar contains five or fewer tabs, iPhone OS displays all of them, equally spaced within the tab bar, as shown in Figure 6-12.

如果应用程序的标签栏有五个或者少于五个的标签，iPhone操作系统可以用相同的大小显示所有标签，如图6-12所示。

Figure 6-12  iPhone OS displays up to five tabs in a tab bar
图6-12 iPhone操作系统在标签栏中显示不多于五个的标签

If your application’s tab bar contains more than five tabs, iPhone OS displays four of them in the tab bar and adds a More tab, as shown in Figure 6-11.

如果应用程序的标签栏包含五个以上的标签，iPhone操作系统会显示其中的四个并增加一个“更多标签”，如图6-11所示

Users tap the More tab to see a list of additional tabs in a separate screen, as shown in Figure 6-13.

用户可以查看一个单独在屏幕上显示的其他选项的列表来查找更多标签，如图6-13所示。

Figure 6-13  Additional tabs are displayed when users tap the More tab
图6-13 当用户点击更多标签的时候其他标签被显示出来

The More screen can also include an Edit button that users can tap to configure the tab bar so that it displays the tabs they use most often. For example, Figure 6-14 shows the Configure screen users see after they tap the Edit button in the iPod application’s More screen.

在其他选项的页面也可以包含一个编辑按钮，用户可以点击这个按钮区设定标签栏来显示他们最常用的标签。例如，图6-14显示的就是用户点击其它选项页面中的编辑按钮后所看到的设定页面。

Figure 6-14  When an application has more than five tabs, users can select their favorite tabs to display in the tab bar
图6-14 当应用程序拥有五个以上的标签时，用户可以选择他们让他们最喜欢的标签显示在标签栏上。

Notice how iPod uses the same tab icons in all three places (the tab bar, the More screen, and the Configure screen). This helps users be confident that each icon means the same thing, regardless of where it’s displayed.

注意iPod在这三个地方使用了相同的标签图标（标签栏其它选项页面，设置页面）。这有助于用户确信无论在哪里显示，每个图标代表的都是相同的一件事情。

在标签栏中标记一个标签

Badging a Tab in a Tab Bar

You can display a badge on a tab to communicate with users in a nonintrusive, understated way. This type of feedback is suitable for communicating information that isn’t critical to the user’s task or context, but that is useful to know. The badge looks similar to the one Phone displays on the Voicemail tab to indicate the number of unheard messages: it is a red oval that appears near the upper right corner of the tab. The white text inside the oval provides the information.

你可以在标签上显示一个标记以便与用户以无干扰，朴素德方式进行沟通。这种类型的反馈适用于通话信息，虽然对用户的项目或其范围内的东西并不重要，但了解这些是很有用的。这种标签类似于在语音信箱标签上显示一个信息来表明未听的信息：它是一个在标签右上角的红色椭圆形的标记。椭圆形里面白色的文字提供了信息。

Associating a badge with a specific tab allows you to connect the information in the badge with a particular mode in your application, even when that mode is not the current one. Figure 6-15 shows an example of a badge on a tab.

将一个标记与一个特定的标签关联，这使你可以在你的应用程序中用一种特别的方式将标记中的信息联系起来，甚至这种方式不是当前方式。图6-15所示的是一个标签上标记的例子。

Figure 6-15  A badge conveys information in a tab bar
图6-15 在标签栏上，一个标记传达了某种信息

Note that a badge can also be displayed on your application icon in the Home screen if you register for Apple Push Notification Service and users agree to allow badging. See “Enabling Push Notifications” for more information on how this works.

请注意，如果你注册了苹果推送通知服务并且用户同意使用标记的话，标记同样可以显示在主页中你的应用程序图标上。关于更多有关苹果推送通知服务时如何工作的请参阅“启动推送通知”。