ios - UItextfield shouldChangeCharactersInRange方法BackSpace不起作用

Question

我实现了这段代码，但是在我按下UITextfield中的Delete按钮之前，退格键不起作用
我想使用Backspace删除。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string  {

    NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:_demo_str];
    for (int i = 0; i < [string length]; i++) {
         unichar c = [string characterAtIndex:i];
         if ([myCharSet characterIsMember:c]) {
            return YES;
      }
    }
    return NO;
  }

Answer 1

试试这个代码。这对我有用

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string  {

  NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:_demo_str];
  for (int i = 0; i < [string length]; i++) {
     unichar c = [string characterAtIndex:i];
     if ([myCharSet characterIsMember:c]) {
        return YES;
     }
     else
     {
         return NO;
     }
  }
   return YES;
}