• Swift


    问题现象:想在页面初始化的时候,使用self.presentViewController方法弹出个告警提示框UIAlertController。但行后报了个如下告警,同时告警框也出不来。
    1
    2015-03-10 09:55:34.197 Test[1140:29622] Warning: Attempt to present <UIAlertController: 0x7c95ca20> on <Test.ViewController: 0x7a6afc60> whose view is not in the window hierarchy!

    解决办法:原来的调用代码是写在viewDidLoad方法中,这个表示视图加载完毕。我们应该把方法调用放到viewDidApper中,这个是UIViewController对象的视图已经加入到窗口时调用。
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    import UIKit
     
    class ViewController: UIViewController ,UIActionSheetDelegate {
        override func viewDidLoad() {
            super.viewDidLoad()
        }
         
        override func viewDidAppear(animated: Bool){
            super.viewDidAppear(animated)
             
            var alertController = UIAlertController(title: "系统提示",
                message: "您确定要离开hangge.com吗?", preferredStyle: UIAlertControllerStyle.Alert)
            var cancelAction = UIAlertAction(title: "取消", style: UIAlertActionStyle.Cancel, handler: nil)
            var okAction = UIAlertAction(title: "好的", style: UIAlertActionStyle.Default, handler: nil)
            alertController.addAction(cancelAction)
            alertController.addAction(okAction)
            self.presentViewController(alertController, animated: true, completion: nil)
        }
           
        override func didReceiveMemoryWarning() {
            super.didReceiveMemoryWarning()
            // Dispose of any resources that can be recreated.
        }
    }
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  • 原文地址:https://www.cnblogs.com/Free-Thinker/p/4838386.html
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