在 applicationDidEnterBackground 之前显示视图或启动屏幕(以避免活动视图屏幕截图) [英] Display a view or splash screen before applicationDidEnterBackground (to avoid active view screenshot)

问题描述

我的应用中有机密信息，所以我想在应用即将移至后台时用启动屏幕隐藏它们.

I have confidential informations in my app, so I would like to hide them with a splash screen when the app is about to be moved to background.

我确实在 iOS6 及更高版本上运行该应用程序.

I do run the app on iOS6 and further.

我试图在 applicationWillResignActive 中显示视图，但问题是即使用户滑动控制面板，它也会显示启动画面.我希望它仅在应用移至后台时显示.

I tried to display the view in applicationWillResignActive but the problem is it display the splash screen even when user swipe control panel for example. I want it to show only when the app is moved to background.

我尝试在 applicationDidEnterBackground 中显示我的 splashScreen，但它需要先截屏，因此在动画期间恢复时会显示信息.

I tried to displayed my splashScreen in applicationDidEnterBackground but it takes the screenShot before so informations are displayed at restoration during the animation.

这里是我想要的精神:

- (void)applicationDidEnterBackground:(UIApplication *)application {
    [_window addSubview:__splashController.view];
}

推荐答案

我认为问题在于你在模拟器中进行测试.在设备上，它应该可以正常工作.

I think the problem is that you are testing in simulator. On device, it should work fine.

我对此进行了测试，它确实有效.当应用进入后台时，添加带有初始图像的图像视图 -

I tested this and it worked. Add an imageview with your splash image when app enters in background -

- (void)applicationDidEnterBackground:(UIApplication *)application
{

        UIImageView *imageView = [[UIImageView alloc] initWithFrame:self.window.bounds];

        imageView.tag = 101;    // Give some decent tagvalue or keep a reference of imageView in self
    //    imageView.backgroundColor = [UIColor redColor];
        [imageView setImage:[UIImage imageNamed:@"Default.png"]];   // assuming Default.png is your splash image's name

        [UIApplication.sharedApplication.keyWindow.subviews.lastObject addSubview:imageView];
}

当应用返回前台时 -

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    UIImageView *imageView = (UIImageView *)[UIApplication.sharedApplication.keyWindow.subviews.lastObject viewWithTag:101];   // search by the same tag value
    [imageView removeFromSuperview];

}

注意 - 在模拟器 (iOS 7.0) 上，当您按两次主页按钮 (Cmd + H) 进行检查时，不会显示添加的子视图，但在设备上它按预期工作(如 paypal，BofA 应用程序)

NOTE - On simulator (iOS 7.0), the added subview is not show when you check by pressing home button twice (Cmd + H), but on device it works as expected (like paypal, BofA apps)

(附加信息)

除了如上所述通过添加子视图/模糊来隐藏/替换敏感信息外，iOS 7 还提供了通过 的 ignoreSnapshotOnNextApplicationLaunch 忽略屏幕快照的功能applicationWillResignActive 或 applicationDidEnterBackground 内的 UIApplication.

In addition to obscuring/replacing sensitive information by adding subview / blur as explained above, iOS 7 provides you ability to ignore the screen snapshot via ignoreSnapshotOnNextApplicationLaunch of UIApplication inside applicationWillResignActive or applicationDidEnterBackground.

UIApplication.h

// Indicate the application should not use the snapshot on next launch, even if there is a valid state restoration archive.
// This should only be called from methods invoked from State Preservation, else it is ignored.
- (void)ignoreSnapshotOnNextApplicationLaunch NS_AVAILABLE_IOS(7_0);

此外，allowScreenShot 标志可以在 限制负载.

Also, allowScreenShot flag can be explored in Restrictions Payload.

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