ios 给textField每四位添加一个空格

#pragma mark - UITextFieldDelegate
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
if (textField == _cardTextField) {
// 四位加一个空格
if ([string isEqualToString:@""]) { // 删除字符
if ((textField.text.length - 2) % 5 == 0) {
textField.text = [textField.text substringToIndex:textField.text.length - 1];
}
return YES;
} else {
if (textField.text.length % 5 == 0) {
textField.text = [NSString stringWithFormat:@"%@ ", textField.text];
}
}
return YES;
}
return YES;
}