?????????????????????UIButton ????????????????????漸???????????????????????????????????
????adjustsImageWhenHighlighted
???????????￡????????????????????????????Щ??????????????????????????NO??
????btn1.adjustsImageWhenHighlighted = NO;
????adjustsImageWhenDisabled
???????????￡????????????????????????????Щ??????????????????????????NO??
????btn1.adjustsImageWhenDisabled = NO;
????showsTouchWhenHighlighted
????????????????YES??????????????????????????????????????Щ?????????
????btn1.showsTouchWhenHighlighted = YES;
??????????????
?????????????????????
????[self.view addSubview:btn1];
????[self.view addSubview:btn2];
?????????д???????
??????????????????????????????????????????????????????????????????Щ????????Щ????????CGRect?????????????????????硣
??????????????????Щ?????? ??Щ????????д??????????
????backgroundRectForBounds   //??????????
????contentRectForBounds // ?????????
????titleRectForContentRect    // ????????????
????imageRectForContentRect     //???????????
????????
????- (CGRect)imageRectForContentRect:(CGRect)bounds{
????return CGRectMake(0.0?? 0.0?? 44?? 44);
????}
?????塢??????
?????????????????????????????????????????????????????????????????????? UIControl ?????????
????-(void)btnPressed:(id)sender{
????UIButton* btn = (UIButton*)sender;
????//???д??????????
????}
????[btn1 addTarget:self action:@selector(btnPressed:) forControlEvents:UIControlEventTouchUpInside];
????????END
????END????δ??????????UIButton??????????????δ?????????: UIBarButtonItem .????UIButton??????????????????????????????????UIButton?????
???????д???????СDemo??????棺UIButtonDemo