IOS以编程方式创buildUIAlertViewController

我正在使用代码（没有故事板）的ViewController。 我试图添加和AlertController

我在.m中声明propery

@property (nonatomic, strong) UIAlertController *alertController; 

并在loadview方法中初始化

 //alertviewController _alertController = [[UIAlertController alloc]initWithNibName:nil bundle:nil]; 

并在viewDidLoad调用alertview：

 _alertController = [UIAlertController alertControllerWithTitle:@"Error display content" message:@"Error connecting to server, no local database" preferredStyle:UIAlertControllerStyleAlert]; UIAlertAction *ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) { LandingPageViewController *viewController = [[LandingPageViewController alloc] initWithNibName:nil bundle:nil]; // viewController.showNavBarBackButton = YES; [[AppDelegate sharedAppDelegate].rootViewController cPushViewController:viewController]; }]; [_alertController addAction:ok]; [self presentViewController:_alertController animated:YES completion:nil]; 

我不知道为什么警报没有显示出来。 有些事情我的代码错了。 如何以编程方式设置和调用alertViewController ？

Answer 1

 - (void)logoutButtonPressed { UIAlertController * alert = [UIAlertController alertControllerWithTitle:@"Logout" message:@"Are You Sure Want to Logout!" preferredStyle:UIAlertControllerStyleAlert]; //Add Buttons UIAlertAction* yesButton = [UIAlertAction actionWithTitle:@"Yes" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action) { //Handle your yes please button action here [self clearAllData]; }]; UIAlertAction* noButton = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action) { //Handle no, thanks button }]; //Add your buttons to alert controller [alert addAction:yesButton]; [alert addAction:noButton]; [self presentViewController:alert animated:YES completion:nil]; } 

Answer 2

而在Swift> = 3 ：

  let alertController = UIAlertController(title: "Some Error", message: "Pleas confirm?", preferredStyle: .alert) let defaultAction = UIAlertAction(title: "OK", style: .default, handler: nil) alertController.addAction(defaultAction) self?.present(alertController, animated: true, completion: nil) 

Answer 3

全局警报控制器，可在所有视图控制器中访问。
用您的函数创buildUIViewController的扩展，以显示具有所需参数参数的警报

 extension UIViewController { func displayalert(title:String, message:String) { let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert) alert.addAction((UIAlertAction(title: "OK", style: .default, handler: { (action) -> Void in alert.dismiss(animated: true, completion: nil) }))) self.present(alert, animated: true, completion: nil) } } 

现在从你的视图控制器调用这个函数：

 class TestViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() self.displayalert(title: <String>, message: <String>) } }