如何在沒有視圖控制器的情況下顯示UIAlertController？場景：用戶點擊視圖控制器上的按鈕。視圖控制器是導航堆棧中的最頂層(顯然)。TAP調用另一個類上調用的實用程序類方法。在那里發生了一件壞事，我想在控件返回到視圖控制器之前在那里顯示一個警告。+ (void)myUtilityMethod {
// do stuff
// something bad happened, display an alert.}這是有可能的UIAlertView(但可能不太恰當)。在這種情況下，您如何表示UIAlertController，就在那里myUtilityMethod?
3 回答
BIG陽
TA貢獻1859條經驗 獲得超6個贊
let alertController: UIAlertController = ...UIApplication.sharedApplication().keyWindow?.rootViewController?.presentViewController(alertController, animated: true, completion: nil)
let alertController: UIAlertController = ...UIApplication.shared.keyWindow?.rootViewController?.present(alertController, animated: true, completion: nil)
梵蒂岡之花
TA貢獻1900條經驗 獲得超5個贊
斯威夫特
let alertController = UIAlertController(title: "title", message: "message", preferredStyle: .alert)//...var rootViewController = UIApplication.shared.keyWindow?.rootViewControllerif let navigationController = rootViewController as? UINavigationController {
rootViewController = navigationController.viewControllers.first}if let tabBarController = rootViewController as? UITabBarController {
rootViewController = tabBarController.selectedViewController}//...rootViewController?.present(alertController, animated: true, completion: nil)目標-C
UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title" message:@"message" preferredStyle:UIAlertControllerStyleAlert];//...id rootViewController = [UIApplication sharedApplication].delegate.window.rootViewController;if([rootViewController isKindOfClass:[UINavigationController class]]){
rootViewController = ((UINavigationController *)rootViewController).viewControllers.firstObject;}if([rootViewController isKindOfClass:[UITabBarController class]]){
rootViewController = ((UITabBarController *)rootViewController).selectedViewController;}//...[rootViewController presentViewController:alertController animated:YES completion:nil];- 3 回答
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