问题
I've seen a lot of answers, but it seems that none of them has worked. I have a programmatically created UIAlertView with two UITextFields. I want to restrict the number of characters :
- 12 characters in first field
- 1 character in second field
First field code:
alertDialog.addTextField { (nameField) in
nameField.placeholder = "Name"
nameField.borderStyle = .roundedRect
nameField.clearButtonMode = .whileEditing
}
And second
alertDialog.addTextField { (keyField) in
keyField.placeholder = "Key"
keyField.borderStyle = .roundedRect
keyField.clearButtonMode = .whileEditing
}
How can I correctly restrict the number (Let's pretend that there will be no paste in these field)
回答1:
Set textField delegates to respective class (in my case self is ViewController)
nameField.delegate = self
keyField.delegate = self
Then you can restrict characters by
extension ViewController : UITextFieldDelegate {
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
switch textField {
case nameField:
if ((textField.text?.length)! + (string.length - range.length)) > 12 {
return false
}
case keyField:
if ((textField.text?.length)! + (string.length - range.length)) > 1 {
return false
}
}
return true
}
}
回答2:
You can add an event like this:
textField1.addTarget(self, action: #selector(YourViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)
textField2.addTarget(self, action: #selector(YourViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)
Then implement this function:
func textFieldDidChange(textField: UITextField) {
if textField == self.textField1 && textField.text.length > 12 {
// Do whaterver you want
}
if textField == self.textField2 && textField.text.length > 1 {
// Do whaterver you want
}
}
来源：https://stackoverflow.com/questions/41280540/restrict-the-number-of-characters-in-uitextfield