使用Swift在UIScrollView中居中图像

Question

I have a picture that is long, that I want to show all scrolling the page from top to bottom, with a ScrollView.

My problem is that the image is all to the right of the page, and there is no way to center it in the middle of the page. Instead, when I double tap the page to zoom the photo, the image come to the center of the page, and there are no problems.

The error is only when I enter to that page and the photo is all to the right, cutted because part of it go outside the page.

I am using Swift, with Autolayout (my app doesn't work without it), and this is the code of the ScrollView. I hope that you can help me...

    override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    navigationItem.title = nameString!

    imageView?.image = UIImage(named: imageName!)
    nameLabel?.text = nameString!

    // 1
    let image = UIImage(named: imageName!)!
    imageView = UIImageView(image: image)
    imageView.frame = CGRect(origin: CGPoint(x: 0, y: 0), size:image.size)
    scrollView.addSubview(imageView)

    // 2
    scrollView.contentSize = image.size

    // 3
    var doubleTapRecognizer = UITapGestureRecognizer(target: self, action: "scrollViewDoubleTapped:")
    doubleTapRecognizer.numberOfTapsRequired = 2
    doubleTapRecognizer.numberOfTouchesRequired = 1
    scrollView.addGestureRecognizer(doubleTapRecognizer)

    // 4
    let scrollViewFrame = scrollView.frame
    let scaleWidth = scrollViewFrame.size.width / scrollView.contentSize.width
    let scaleHeight = scrollViewFrame.size.height / scrollView.contentSize.height
    let minScale = min(scaleWidth, scaleHeight);
    scrollView.minimumZoomScale = minScale;

    // 5
    scrollView.maximumZoomScale = 1.0
    scrollView.zoomScale = minScale;

    // 6
    centerScrollViewContents()
}

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) / 2.0
    } else {
        contentsFrame.origin.x = 0.0
    }

    if contentsFrame.size.height < boundsSize.height {
        contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height) / 2.0
    } else {
        contentsFrame.origin.y = 0.0
    }

    imageView.frame = contentsFrame
}

func scrollViewDoubleTapped(recognizer: UITapGestureRecognizer) {
    // 1
    let pointInView = recognizer.locationInView(imageView)

    // 2
    var newZoomScale = scrollView.zoomScale * 1.5
    newZoomScale = min(newZoomScale, scrollView.maximumZoomScale)

    // 3
    let scrollViewSize = scrollView.bounds.size
    let w = scrollViewSize.width / newZoomScale
    let h = scrollViewSize.height / newZoomScale
    let x = pointInView.x - (w / 2.0)
    let y = pointInView.y - (h / 2.0)

    let rectToZoomTo = CGRectMake(x, y, w, h);

    // 4
    scrollView.zoomToRect(rectToZoomTo, animated: true)
}

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

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

Where is the problem? Thank you all

Answer 1

解决了，只需要取消选中大小类并删除LaunchScreen大小即可。