How to detect number length in UITextField? - ios

Question

There is a UITextField with name numbercontent, after entering 8 numbers, it will automatically call the next function. Following is my code
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
if (self.numbercontent.text.length == 7) {
[self.numbercontent resignFirstResponder];
[self stopFly];
}
return YES;
}
But there's a bug
when I enter the 8th number, it will automatically call the next function, but the 8th number isn't shown in the UITextField.
If Change self.numbercontent.text.length == 7 to self.numbercontent.text.length > 7, the 8th number is shown in the UITextField, but I need to enter one more number to call the next function, how to fix this bug, thanks.

Answer 1

Try this, instead of shouldChangeCharactersInRange,
[_txtNum addTarget:self action:#selector(didChangeText:) forControlEvents:UIControlEventEditingChanged];
and then add this method,
-(void)didChangeText:(UITextField*)sender
{
if(sender.text.length==8)
{
[self stopFly];
[self.txtNum resignFirstResponder];
}
}

Answer 2

Although answer suggested by #DhavalBhimani is the standard way to handle this, but alternatives can be used with current approach like:
In Objective-C:
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
NSString *updatedString = [textField.text stringByReplacingCharactersInRange:range withString:string];
if (textField.text.length == 7) {
textField.text = updatedString;
[textField resignFirstResponder];
[self stopFly];
}
return YES;
}
In Swift 4.0:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
if textField.text?.count == 7 {
textField.text = updatedString
self.view.endEditing(true)
}
return true
}

Answer 3

Use this.
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
// _textLenghtLimit = your text max lenght
if (_textLenghtLimit > 0) {
if ((range.location >= _textLenghtLimit || textField.text.length + 1 > _textLenghtLimit) && range.length == 0) {
return NO;
}
}
return YES;
}