TextField和TextView限制输入字数长度

 - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
 NSInteger existedLength = textField.text.length;
 NSInteger selectedLength = range.length;
 NSInteger replaceLength = string.length;
 NSInteger pointLength = existedLength - selectedLength + replaceLength;
 //超过16位 就不能在输入了
 if (pointLength > 16) {
  return NO;
 }else{
  return YES;
 }
 
} 

 -(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString*)text
{
 //这个判断相当于是textfield中的点击return的代理方法
 if ([text isEqualToString:@"\n"]) {
  [textView resignFirstResponder];
  return NO;
 }
 
 //在输入过程中 判断加上输入的字符 是否超过限定字数
 NSString *str = [NSString stringWithFormat:@"%@%@", textView.text, text];
 if (str.length > 500)
 {
  textView.text = [textView.text substringToIndex:500];
  return NO;
 }
 return YES;
}