Zoom InOut UIImageView

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Create UIScrollView instance

let scrollview = UIScrollView.init(frame: self.view.bounds)

And then set these properties:

scrollView.minimumZoomScale = 0.1
scrollView.maximumZoomScale = 4.0
scrollView.zoomScale = 1.0
scrollview.delegate = self as? UIScrollViewDelegate

To zoom in and out image we must specify the amount the user can zoom in and out. We do this by setting values of the scroll view’s minimumZoomScale and maximumZoomScale properties. Both of these are set to 1.0 by default.

And zoomScale to 1.0 which specify the zoom factor for the minimum and maximum zooming.

To support zooming, we must set a delegate for your scroll view. The delegate object must conform to the UIScrollViewDelegate protocol. That delegate class must implement the viewForZoomingInScrollView() method and return the view to zoom.

Modify your ViewController as shown

class ViewController: UIViewController, UIScrollViewDelegate

Then add the following delegate function to the class.

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

Now create UIImageView instance

Make this variable as class variable

var imageView:UIImageView = UIImageView.init(image: UIImage.init(named: "someImage.jpg"))

And then add it to scrollview

scrollView?.addSubview(imageView)

Reference

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UIScrollView:
* Zoom InOut UIImageView

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12 UIView
15 UIColor
26 UIImage
28 CALayer
30 NSDate
34 UIScrollView
40 iBeacon
49 NSTimer
79 NSURL
87 AWS SDK
96 NSData
101 Segues
104 EventKit
105 NSBundle
106 SiriKit
111 StoreKit
117 3D Touch
119 Keychain
122 Block
141 AirDrop
144 UISlider
145 Carthage
146 HealthKit
151 plist
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166 Simulator
168 NSArray
169 OpenGL
175 Core Data
179 MyLayout
180 UIFont
189 Security
200 Codable