退出应用程序后隐藏用户界面 [英] Hide UI after resigning application

问题描述

问题如下:

我的应用可以使用密码保护.当用户按下主页按钮时，应用程序退出非活动状态.重新打开后，应用程序显示输入密码"屏幕.但是在显示之前，会先看到初始内容屏幕.同样，如果在按下主页按钮之后用户进入预览模式(两次按下主页按钮)，则预览显示的是内容屏幕，而不是密码屏幕.

My app can be protected with a password. When the user presses home button, application resigns inactive. After reopening it, app shows "enter password" screen. But before it shows up, the initial content screen is visible for a moment. Also if, after pressing home button, user enters preview mode (home button double pressed), preview shows content screen, not password screen.

所以这是两个问题:

1. 如何在应用程序被辞职前将UI(更改为密码屏幕或某些占位符)更改为UI，以便在预览模式下用户将看到内容屏幕以外的其他内容.
2. 当应用程序再次激活时，如何使应用程序暂时不显示内容屏幕(在密码屏幕之前).

感谢您的帮助.

推荐答案

来自

移至后台该怎么做

应用程序可以使用其applicationDidEnterBackground:方法进行准备移至背景状态.移至后台时，所有应用程序应执行以下操作:

Apps can use their applicationDidEnterBackground: method to prepare for moving to the background state. When moving to the background, all apps should do the following:

• 准备拍照.applicationDidEnterBackground:方法返回，系统接受应用程序用户界面的图片，并将生成的图片用于过渡动画.如果界面中的任何视图包含敏感信息，您应该先隐藏或修改这些视图applicationDidEnterBackground:方法返回.

• Prepare to have their picture taken. When the applicationDidEnterBackground: method returns, the system takes a picture of your app’s user interface and uses the resulting image for transition animations. If any views in your interface contain sensitive information, you should hide or modify those views before the applicationDidEnterBackground: method returns.

因此，在您的 applicationDidEnterBackground 方法中，您应该隐藏主视图并显示登录"视图.

So, in your applicationDidEnterBackground method you should hide your main view and present your 'login' view.

更新经过更多研究，结果发现您无法提供视图控制器-您只能影响根窗口.我已经在此答案中测试了该解决方案- Display一个视图或初始屏幕，位于applicationDidEnterBackground之前(以避免活动视图屏幕截图)，它可以正常工作-因此，您可以创建一个显示登录屏幕的图像并将其放在用户界面的顶部.

Update After a bit more research, it turns out you can't present a view controller - you can only affect the root window. I have tested the solution in this answer - Display a view or splash screen before applicationDidEnterBackground (to avoid active view screenshot) and it works - So you can create an image that shows your login screen and put that over the top of your UI.

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