IOS学习 scrollView的单张图片缩放

- (void)initViewController

{    

    //设置scrollview

    _scrollView = [[UIScrollViewalloc]initWithFrame:CGRectMake(0,20,VIEW_WIDTH ,VIEW_HEIGHT)]; //屏幕宽度    

    [self.viewaddSubview:_scrollView];

    //设置内容大小

    _scrollView.contentSize =CGSizeMake(VIEW_WIDTH,VIEW_HEIGHT);

    

    //缩放大小比例

    _scrollView.minimumZoomScale =0.3;

    _scrollView.maximumZoomScale =3;

    

    //默认YES，缩放时有反弹效果

    _scrollView.bouncesZoom =NO; //无反弹效果，一般不用

    

    //设置图片

    imageView = [[UIImageViewalloc]initWithFrame:CGRectMake(0,0, VIEW_WIDTH,VIEW_HEIGHT)];

    imageView.image=[UIImageimageNamed:@"background4"];

    [_scrollView addSubview:imageView];

  

    //设置代理

    _scrollView.delegate=self;

}

#pragma mark - scrollView Delegate

 //返回一个放大或者缩小的视图

 - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView

 {

     returnimageView; //只能处理单张图片

 }

 //开始放大或者缩小

 - (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:

 (UIView *)view

 {

     NSLog(@"crollViewWillBeginZooming");

 }

 

 //缩放结束时

 - (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale

 {

     //scale 缩放的比例

     NSLog(@"scrollViewDidEndZooming %f",scale);

 }

 

 //视图已经放大或缩小

 - (void)scrollViewDidZoom:(UIScrollView *)scrollView

 {

     NSLog(@"scrollViewDidZoom");

 }