，随便点击屏幕任何位子都可以resignFirstResponder，隐藏键盘的两种方法

UIButton类型为UIButtonTypeCustom, 添加一个方法    

[button addTarget:self action:@selector(hideKeyboard) forControlEvents:UIControlEventTouchUpInside];

方法一

-(void)hideKeyboard

{

    [myTextfield resignFirstResponder];

}

方法二

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

{

    [_userNumber resignFirstResponder];

    [_userPassword resignFirstResponder];

}