Xcode Pinch缩放肖像风景

Question

我使用以下代码进行缩放缩放

scroll = [[UIScrollView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];

scroll.backgroundColor = [UIColor clearColor];
scroll.delegate = self;

scroll.contentSize = _imageView.frame.size;
[scroll addGestureRecognizer:tap];

scroll.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"main_bg_PiPad"]];
[scroll addSubview:_imageView];
[scroll addSubview:_viewFrameCapture];
_viewFrameCapture.hidden=YES;
scroll.minimumZoomScale = 1.0;
scroll.maximumZoomScale = 5.0;
[scroll setZoomScale:scroll.minimumZoomScale];
self.view = scroll;

一切都对我很好。但问题是当我处于横向模式时，捏缩放工作正常，当我移动到纵向模式时，捏放大不能正常工作，当我缩小图像尺寸并移除手指时，它立即调整为原始图像尺寸，任何人都可以帮我解决这个问题。