UIAlertController不應該顯示

我正在使用警報控制器創建登錄應用程序，如果用戶沒有正確數量的密碼字符，則不應讓用戶繼續。當我輸入正確的金額時，警報控制器彈出並且不允許我繼續。我的代碼中不應該有什麼東西嗎？UIAlertController不應該顯示

func alertDisplay() { 

    let alertController = UIAlertController(title: "Alert", message: "Five characters or more is required to login", preferredStyle: UIAlertControllerStyle.Alert) 

    let cancelAction = UIAlertAction(title: "Cancel", style: .Cancel) {ACTION -> Void in 
     // Does nothing 
    } 
    let okAction = UIAlertAction(title: "OK", style: .Default) { action -> Void in 
     // does nothing also 
    } 
    alertController.addAction(cancelAction) 
    alertController.addAction(okAction) 

    self.presentViewController(alertController, animated: true, completion: nil) 
    self.dismissViewControllerAnimated(true, completion: nil) 

    let allowedChars = 15 
    let passwordCount = passwordField.text?.characters.count 

    if passwordCount <= allowedChars { 
     // allow user to continue if the amount of characters is less than 15 
     alertController.viewDidAppear(false) 

    } else { 
     // allow user to not be able to continue if they have too many characters 

     alertController.viewDidAppear(true) 
    } 
}

來源

2016-04-18 Terril320

除非你覆蓋'viewWillAppear中/ disappear'，你不應該直接調用這些方法。在調用'presentViewController'後立即調用'dismissViewController'：我不確定這有一個定義良好的行爲。你不應該對抗UIKit（如果它看起來像一個黑客，你可能做錯了;） – Vinzzz

另外一件事我認爲沒有必要在這裏取消按鈕。 –

替換：

self.presentViewController(alertController, animated: true, completion: nil) 
self.dismissViewControllerAnimated(true, completion: nil) 

let allowedChars = 15 
let passwordCount = passwordField.text?.characters.count 

if passwordCount <= allowedChars { 
    // allow user to continue if the amount of characters is less than 15 
    alertController.viewDidAppear(false) 

} else { 
    // allow user to not be able to continue if they have too many characters 

    alertController.viewDidAppear(true) 
}

有了：

let allowedChars = 15 
let passwordCount = passwordField.text?.characters.count 

if passwordCount > allowedChars { 
    self.presentViewController(alertController, animated: true, completion: nil) 
}

來源

2016-04-18 18:02:20

UIAlertController不應該顯示

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