如何从视图中呈现UIAlertController？

Question

Each cell in my collection view has a button and a textfield.

When the button is pressed I want to display an alert if the text field is empty.

In my custom collection view cell I have:

func displayAlert(title: String, error: String) {
 var alert = UIAlertController(title: title, message: error, preferredStyle: UIAlertControllerStyle.Alert)
 alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { action in
 alert.dismissViewControllerAnimated(true, completion: nil)
 }))
 self.presentViewController(alert, animated: true, completion: nil)
}

func redeemButtonPressed(sender: UIButton!) {
 if enterCodeTextField.text == "" {
  displayAlert("Something went wrong", error: "Please enter a valid code")
}

Answer 1

尝试使用alert.show（）作为显示警报的方式。

Answer 2

Try this for your function:

func redeemButtonPressed(sender: UIButton!) {
if enterCodeTextField.text == " "{

        let alert = UIAlertView()
        alert.title = "Alert Title here"
        alert.message = "Message Here"
        alert.addButtonWithTitle("Understood")
        alert.show()

    }