在UIAlertController中删除textField周围的填充和边框

Question

I'm attempting to implement a textfield inside a UIAlertController in Swift in iOS 9.3, somehow I'm getting padding and a top border around the textfield.

Please see the below screenshot, I've added a thick border around the textfield to highlight the padding and top border/line.

The code for my UIAlertController:

func handleLoginForgotPassword() {
    // create alert controller
    let alertController = UIAlertController(title: "Password Reset", message: "\nEnter your email below and press Reset to reset your password.\n", preferredStyle: .Alert)

    // create text field for email
    alertController.addTextFieldWithConfigurationHandler { textField -> Void in
        let tf = textField
        tf.placeholder = "Email Address"
        tf.autocorrectionType = .No
        tf.autocapitalizationType = .None
        tf.backgroundColor = UIColor.whiteColor()    

        tf.layer.borderWidth = 4.0
        tf.heightAnchor.constraintEqualToConstant(50).active = true

        // pull email from emailTextField if it exists
        tf.text = self.emailTextField.text
    }

    // create "OK" alert action
    let actionReset = UIAlertAction(title: "Reset", style: UIAlertActionStyle.Default) {
        UIAlertAction in
        NSLog("YES Pressed")

        // do something

        return
    }
    // create "Cancel" alert action
    let actionCancel = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel) {
        UIAlertAction in
        NSLog("NO Pressed")    

        // do something

        return
    }

    // add the actions
    alertController.addAction(actionReset)
    alertController.addAction(actionCancel)

    // present the controller
    self.presentViewController(alertController, animated: true, completion: nil)
}

This behaviour seems odd and I can't find it referenced when searching for a similar issue.

Answer 1

The constraintEqualToConstant function is only available from iOS 9.0, you need to add checking to your code if you want to support iOS version older than 9.0. This could be the one causing the issue.

if #available(iOS 9.0, *) 
{
  tf.heightAnchor.constraintEqualToConstant(50).active = true
} else 
{
  // Fallback on earlier versions
}