UITextField限制字符长度

UITextField *nameTxetField=[[UITextField alloc] initWithFrame:CGRectMake(50, 100, 200, 30)];
    [nameTxetField addTarget:self action:@selector(limitTextlength:) forControlEvents:UIControlEventEditingChanged];

-(void)limitTextlength:(UITextField *)textField{
    if ([textField.text length]>16) {
        textField.text=[textField.text substringToIndex:16];
    }
}