UIImageView 在 UIScrollView 中捏缩放

我对使用 UIScrollView 的捏合缩放功能感到满意。但问题是滚动视图中图像的长宽比。

目前，我有这个，下图：

但我希望图像适合屏幕，如下图所示：

景观也有同样的行为。我怎样才能实现这个目标？

下面是代码：

- (void)viewDidLoad
{
    UIImage *image = [UIImage imageWithData:appDelegate.selectedOriginalImage];
    imgView.image = image;
    CGSize imageSize = image.size;
    CGRect rect = CGRectMake(0, 0, imageSize.width, imageSize.height);
    imgView.frame = rect;
    scrollView.contentSize = CGSizeMake(imgView.frame.size.width, imgView.frame.size.height);
    scrollView.maximumZoomScale = 4.0;
    scrollView.minimumZoomScale = 1.0;
    scrollView.delegate = self;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    UIImage *image = [UIImage imageWithData:appDelegate.selectedOriginalImage];
    CGSize imageSize = image.size;
    CGRect rect = CGRectMake(0, 0, imageSize.width, imageSize.height);
    imgView.frame = rect;

    [scrollView setContentOffset:CGPointMake(0, 0)]; 

    return YES;
}

您将 UIImageView 设置为图像的原始大小，而不是包含该图像的 UIScrollView 的大小。

- (void)viewDidLoad
{
    UIImage *image = [UIImage imageWithData:appDelegate.selectedOriginalImage];
    imgView.image = image;

    imgView.frame = scrollView.bounds;
    [imgView setContentMode:UIViewContentModeScaleAspectFit];
    scrollView.contentSize = CGSizeMake(imgView.frame.size.width, imgView.frame.size.height);
    scrollView.maximumZoomScale = 4.0;
    scrollView.minimumZoomScale = 1.0;
    scrollView.delegate = self;
}

记得在 viewToZoom 委托方法上返回 imgView