ios - UITextField的leftView 点击属性问题

给UITextField添加leftView后， 需要监听leftView点击事件，添加target后，点击事件无法监听

代码如下

        UIButton *cleanButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 15, 15)];
        [cleanButton setBackgroundImage:[UIImage imageNamed:@"clean_select_member"]
                               forState:UIControlStateNormal];
        [cleanButton addTarget:self
                        action:@selector(cleanSendMessageToUser)
              forControlEvents:UIControlEventTouchUpInside];
        self.inputTextField.leftView = cleanButton;
        self.inputTextField.leftViewMode = UITextFieldViewModeUnlessEditing;

求解