ScrollView上的图片缩放

野性酷女 2023-10-17 03:52 4阅读 0赞

代码如下：

- (void)viewDidLoad
    {
        [super viewDidLoad];
        //创建一个视图背景
        _imageView = [[UIImageView alloc]initWithFrame:_scrollView.bounds];
        _imageView.image = [UIImage imageNamed:@"p3.jpg"];
        [_scrollView addSubview:_imageView];
        
        //设置代理；
        _scrollView.delegate = self;
        
        //设置scrollView最大放大比例，之前的倍数,默认为1
        _scrollView.maximumZoomScale = 2;
        
        //设置scrollView最小缩小比例，之前的倍数,默认为1，0—1之间
        _scrollView.minimumZoomScale = 0.5;
        
        //缩放的反弹效果
        //_scrollView.bouncesZoom = NO;
        
        //上下左右预留的空间
        //_scrollView.contentInset = UIEdgeInsetsMake(40, 40, 40, 40);
    }
    
    //设置scrollView所放的view，这个view必须是scrollView的子view
    - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
    {
        return _imageView;
    }
    
    //scrollView缩放时调用
    - (void)scrollViewDidZoom:(UIScrollView *)scrollView
    {
        NSLog(@"缩放%f",scrollView.zoomScale);
    //    if (scrollView.zoomScale<1)
    //    {
    //        scrollView.frame = CGRectMake(scrollView.frame.size.width*(1-scrollView.zoomScale)/2, scrollView.frame.size.height*(1-scrollView.zoomScale)/2, scrollView.frame.size.width, scrollView.frame.size.height);
    //    }
    //    else
    //    {
    //        scrollView.frame = CGRectMake(0, 0, scrollView.frame.size.width, scrollView.frame.size.height);
    //    }
        
        if (scrollView.zoomScale<1)
        {
            scrollView.contentInset=UIEdgeInsetsMake(scrollView.frame.size.height*(1-scrollView.zoomScale)/2, scrollView.frame.size.width*(1-scrollView.zoomScale)/2,0,0);
        }
        else
        {
            scrollView.contentInset = UIEdgeInsetsMake(0,0,0,0);
        }
    }

按住键盘上的option键，然后单击鼠标  
效果图如下：

![Center][]

[Center]: https://img-blog.csdn.net/20160625161116542?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center