UIButton 应用选择状态（附：UIButton 常用状态）

    NSString * path = [[NSBundle mainBundle]pathForResource:@"alien" ofType:@"png"];

    UIImage *image = [[UIImage alloc] initWithContentsOfFile:path];
    NSString* path2 = [[NSBundle mainBundle]pathForResource:@"spider" ofType:@"png"];
    UIImage * image2 =[[UIImage alloc]initWithContentsOfFile:path2];
//创建两张图片
    UIButton *button = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];
    [button setBackgroundImage:image forState:UIControlStateNormal];//设置正常状态
    [button setBackgroundImage:image2 forState:UIControlStateSelected];//设置选择状态
    [button addTarget:self action:@selector(click:) forControlEvents:UIControlEventTouchUpInside];
//添加事件
   
    button.adjustsImageWhenHighlighted = FALSE;
    [self.view addSubview:button];

-(void)click:(id)sender
{
UIButton *u = (UIButton *)sender;
u.selected = YES;//选择状态设置为YES,如果有其他按钮 先把其他按钮的selected设置为NO，
}

UIButton状态:

UIControlStateNormal          // 正常状态   

UIControlStateHighlighted     // 高亮状态   

UIControlStateDisabled        // 禁用状态    

UIControlStateSelected        // 选中状态    

UIControlStateApplication     //     

UIControlStateReserved        // 保留状态