ios - tag的使用

 UIButton* buttonByTag   =   (UIButton*)[self viewWithTag:100]; //通过tag获得相应的uibutton
    if( buttonByTag != nil )
        [buttonByTag removeFromSuperview];
//如果button不为空，则清除之前的显示

//初始化button
    UIButton* button    =   [UIButton buttonWithType:UIButtonTypeCustom];
    button.tag          =   100;
    UIImage* image     =   [GameMgr getImage:png type:1];
    [button setBackgroundImage:image3 forState:0];
    button.frame        =   CGRectMake(0, 0, 100, 100);
    [self addSubview:button3];