带有ImageView的UIScrollView不能垂直滚动

Question

我有一个UIImageView它的图像大于屏幕尺寸.我有这个UIImageView作为子视图UIScrollView.现在,我无法向下滚动.查看整个图像.但缩放功能正常.

@IBOutlet weak var scrollView: UIScrollView!

var imageView = UIImageView();

override func viewDidLoad() {
    super.viewDidLoad()
}

func centerScrollViewContents(){
    let boundsSize = scrollView.bounds.size
    var contentsFrame = imageView.frame

    if contentsFrame.size.width < boundsSize.width {
       contentsFrame.origin.x = (boundsSize.width - contentsFrame.size.width) / 2
    }
    else { 
       contentsFrame.origin.x = 0
    }

    if contentsFrame.size.height < boundsSize.height {            
        contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height) / 2
    }
    else {
        contentsFrame.origin.y = 0
    }

    imageView.frame = contentsFrame
   // scrollView.frame = contentsFrame        
}

func scrollViewDidZoom(scrollView: UIScrollView) {
    centerScrollViewContents()
}

func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
    return imageView
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

    // Dispose of any resources that can be recreated.
}

override func viewDidAppear(animated: Bool) {

    scrollView.delegate = self
    imageView.frame = CGRectMake(0, 0, scrollView.frame.size.width, scrollView.frame.size.height)

   // imageView.contentMode = UIViewContentMode.ScaleAspectFill
   // imageView.clipsToBounds = true
    imageView.image = UIImage(named: imgstr)

    var imagee = UIImage(named: imgstr)
    let size = imagee?.size
   // imageView.frame = CGRectMake(0, 0, size.width!, size.height!)
    imageView.contentMode = .Top
    scrollView.addSubview(imageView)

    scrollView.contentSize = size!
    let scrollViewFrame = scrollView.frame
    let scaleWidth = scrollViewFrame.size.width / scrollView.contentSize.width
    let scaleHeight = scrollViewFrame.size.height / scrollView.contentSize.height
    let minScale = min(scaleHeight, scaleWidth)

    scrollView.minimumZoomScale = 1
    scrollView.maximumZoomScale = 5
    scrollView.zoomScale = minScale

    centerScrollViewContents()   
}

Answer 1

确保您已启用滚动视图的用户交互：scrollview.userInteractionEnabled=YES