Zoom a view controller in swift

Question

I am creating an iOS application (swift) where I have multiple labels in a view controller. I am not using any scrollView. I need to zoom the view controller on a pinch gesture. I know I have found solutions with scroll view, but I don't want to implement scrollView in my view controller. Any help would be appreciated! Thank You.

UPDATED:

I have implemented a scrollView in view controller. I have added a view in scrollview and the view contains some labels, but the issues that I am facing is now are:

1. Zoom does not stay static. That is as soon as I release my fingers, the scrollview is automatically zoomed to original as it was.

2. When the view controller is in original state, the app crashes.

here is my code:

@IBOutlet weak var scrollView: UIScrollView!

@IBOutlet var viewThis: UIView!

override func viewDidLoad() {

    super.viewDidLoad()

    scrollView.delegate = self

    //let gesture = UIPinchGestureRecognizer(target: self, action: #selector(pinchAction(sender:)))
    //self.view.addGestureRecognizer(gesture)

    // Do any additional setup after loading the view.

    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

    scrollView.maximumZoomScale = 1.0

    scrollView.zoomScale = minScale;
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func viewForZooming(in scrollView: UIScrollView) -> UIView? {

    return viewThis
}

Answer 1

Thanks to @YunCHEN for helping me with this. He gave me an idea what's going on in the code. I was facing an issue such that while zooming out, my app used to crash because it was getting out of limits when compared to the view width and height. I have updated an answer if somebody finds the same issue in future.

Step 1: Add a scrollView in view controller.

Step 2: Add a view on scrollView.

Step 3: Add all your items/objects from objects library on this view.

Step 4: Bind the scrollView and view to the view controller in code. Also add a UIScrollViewDelegate.

Step 5: Do as done below.

Here is the code:

@IBOutlet weak var scrollView: UIScrollView!

@IBOutlet var viewThis: UIView!

override func viewDidLoad() {

    super.viewDidLoad()

    scrollView.delegate = self

    scrollView.minimumZoomScale = 1.0;

    scrollView.maximumZoomScale = 3.0

    scrollView.zoomScale = 1.0
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func viewForZooming(in scrollView: UIScrollView) -> UIView? {

    return viewThis
}

Again thanks to @YunCHEN for helping me out!

Answer 2

UIView's transform property can make a view and its sub views smaller or bigger, like zooming effect. Example working with UIPinchGestureRecognizer:

class ExampleViewController: UIViewController {

    var previousScale:CGFloat = 1.0

    override func viewDidLoad() {
        super.viewDidLoad()

        let gesture = UIPinchGestureRecognizer(target: self, action: #selector(pinchAction(sender:)))
        self.view.addGestureRecognizer(gesture)
    }

    func pinchAction(sender:UIPinchGestureRecognizer) {
        let scale:CGFloat = previousScale * sender.scale
        self.view.transform = CGAffineTransform(scaleX: scale, y: scale);

        previousScale = sender.scale
    }
}

And maybe you need to consider adjusting position of view after zooming, use CGAffineTransform(translationX: , y: ) to do that.

Still agree with that the UIScrollView is the easiest way to do zooming.