UITableView的默认Cell，是有点击选中的高亮背景色的，UIButton也可以通过设置不同状态的背景图片来实现高亮，那么如何给自定义视图添加高亮呢？

一个技术上可行的方法就是重写UIView的各种touches方法，自己记录点击选中，点击取消等状态，不过很繁琐。

还有一个是重写UIControl的下面四个方法，下面四个方法将点击选中，取消等状态处理简化了

//是否可以开始追踪事件
- (BOOL)beginTrackingWithTouch:(UITouch *)touch withEvent:(nullable UIEvent *)event;

//是否持续追踪事件
- (BOOL)continueTrackingWithTouch:(UITouch *)touch withEvent:(nullable UIEvent *)event;

//事件追踪结束
- (void)endTrackingWithTouch:(nullable UITouch *)touch withEvent:(nullable UIEvent *)event; // touch is sometimes nil if cancelTracking calls through to this.

//事件追踪取消
- (void)cancelTrackingWithEvent:(nullable UIEvent *)event;   // event may be nil if cancelled for non-event reasons, e.g. 

具体示例

- (BOOL)beginTrackingWithTouch:(UITouch *)touch withEvent:(nullable UIEvent *)event
{
    BOOL b = [super beginTrackingWithTouch:touch withEvent:event];
    if (b) {
    如果开始追踪，那么就高亮显示
        [super setBackgroundColor:高亮色];
    }
    return b;
}
- (void)endTrackingWithTouch:(nullable UITouch *)touch withEvent:(nullable UIEvent *)event
{
    [super endTrackingWithTouch:touch withEvent:event];
    //结束追踪 恢复原始背景色
    [super setBackgroundColor:原始背景色];
}

- (void)cancelTrackingWithEvent:(nullable UIEvent *)event
{
    [super cancelTrackingWithEvent:event];
    //取消追踪 恢复原始背景色
    [super setBackgroundColor:原始背景色];
}