ios - 当应用程序进入后台时如何在应用程序中全局隐藏 UIAlertController

Question

我需要一个系统来隐藏所有UIAlertController当她进入后台时在我的应用程序中。目前我使用 BaseViewController我所有的类(class)UIViewControllers注册“进入后台”通知并引用 UIAlertViewController .这个BaseViewController如果弹出窗口可见，则隐藏它。它有效，但不实用。

另一种方法是子类化，但 Apple doc 说:

The UIAlertController class is intended to be used as-is and does not support subclassing. The view hierarchy for this class is private and must not be modified.

您是否有更好的解决方案，不涉及子类 UIViewController谁包含 UIAlertController ?

Answer 1

请使用此代码，您需要获取顶 View Controller
使用此方法获取顶 View Controller

- (id)getTopViewController {

    UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;

    while (topController.presentedViewController) {
        topController = topController.presentedViewController;
    }
    if (![topController isKindOfClass:[NSNull class]]) {
        return topController;
    }
}


- (void)applicationDidEnterBackground:(NSNotification *)notification {

    UIViewController *viewOb = [self getTopViewController];

    // check  UIViewController is  UIAlertController
    if ([view isKindOfClass:[UIAlertController class]]) {
        NSLog(@"%@",view);
        [viewOb dismissViewControllerAnimated:YES completion:nil];
    }
}

然后用 hot viewController 关闭 ViewController