MagnifyingGlass

A magnifying glass view for iOS platform written in Swift. Easily create and customize magnifying glass effect (with optional crosshair) on given view. Available as a Swift package.

Image credit: "Crouching Tiger, Hidden Dragon" by Philippe Vieux-Jeanton is marked with CC0 1.0

Usage/Examples

Instantiate MagnifyingGlassView in any view or view controller by using convenience initializer:

let magnifyingGlass = MagnifyingGlassView(offset: CGPoint = CGPoint.zero,
                                          radius: CGFloat = 50.0,
                                          scale: CGFloat = 2.0,
                                          borderColor: UIColor = UIColor.lightGray,
                                          borderWidth: CGFloat = 3.0,
                                          showsCrosshair: Bool = true,
                                          crosshairColor: UIColor = UIColor.lightGray,
                                          crosshairWidth: CGFloat = 0.5)

All arguments have default values so you can use only ones that you need. You can also directly access any of these parameters at any time of the view lifecycle.

When you're ready to show magnifying glass just give it the view that you'd like to magnify and specify magnication location:

magnifyingGlass.magnifiedView = view
magnifyingGlass.magnify(at: location) // location: CGPoint

When you want to hide magnifying glass set magnifiedView to nil:

magnifyingGlass.magnifiedView = nil

Here's more complete example use of MagnifyingGlassView in view controller where glass follows touch point:

import UIKit
import MagnifyingGlass

class ViewController: UIViewController {
    
    let magnifyingGlass = MagnifyingGlassView(offset: CGPoint(x: 50.0, y: -50.0), radius: 50.0, scale: 2.5)
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.isMultipleTouchEnabled = false
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        let location = touches.first!.location(in: view)
        
        magnifyingGlass.magnifiedView = view
        magnifyingGlass.magnify(at: location)
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        let location = touches.first!.location(in: view)

        magnifyingGlass.magnify(at: location)
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        magnifyingGlass.magnifiedView = nil
    }
    
    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        magnifyingGlass.magnifiedView = nil
    }
    
}

License

MIT