自定义checkbox in iOS

做项目的过程中发现，IOS的SDK中并没有单选框控件。所以想办法将UIButton自定义成checkbox.方法如下

UIImage *uncheckedImg=[UIImage imageNamed:@"check_2x.png"];

UIImage *checkedImg=[UIImage imageNamed:@"checked_2x.png"];

UIButton *checkboxBtn=[UIButton buttonwithType:UIButtonTypeCustom];

[checkboxBtn setBackgroundImage:uncheckedImg forState:UIControlStateNormal];

[checkboxBtn setBackgroundImage:checkedImg forControl:UIControlStateSelected];

[checkboxBtn addTarget:self action:@selector(chooseBox1:) forControlEvents:UIControlEventTouchupInside];

粗体字部分一定要实现，否则不会有按下button打勾的效果