CALayersTutorialExample.swift

//
//  ViewController.swift
//  CALayerLearning
//
//  update of code from the following tutorial
//  https://www.raywenderlich.com/90488/calayer-in-ios-with-swift-10-examples
//  see also https://github.com/scotteg/LayerPlayer

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var viewForLayer: UIView!
    
    @IBAction func viewTap(_ sender: UITapGestureRecognizer) {
        toggleLayerShadowOpacity((sender.view?.layer)!)
    }
    
    @IBAction func viewPinch(_ sender: UIPinchGestureRecognizer) {
        scaleView((sender.view?.layer)!, scale:sender.scale)
    }
    
    
    var myLayer:CALayer {
        get { return viewForLayer.layer }
    }
    
    func setupLayer(_ layer:CALayer) {
        layer.backgroundColor = UIColor.blue.cgColor
        layer.borderWidth = 100.0
        layer.borderColor = UIColor.red.cgColor
        layer.shadowOpacity = 0.7
        layer.shadowRadius = 10.0
        layer.contents = UIImage(named: "star")?.cgImage
        layer.contentsGravity = kCAGravityCenter
    }
    
    func toggleLayerShadowOpacity(_ layer:CALayer) {
        layer.shadowOpacity = layer.shadowOpacity == 0.7 ? 0.0 : 0.7
    }
    
    func scaleView(_ layer:CALayer, scale:CGFloat) {
        let offset: CGFloat = scale < 1 ? 5.0 : -5.0
        
        let oldFrame = layer.frame
        let oldOrigin = oldFrame.origin
        let newOrigin = CGPoint(x: oldOrigin.x + offset, y: oldOrigin.y + offset)
        let newSize = CGSize(width: oldFrame.width + (offset * -2.0), height: oldFrame.height + (offset * -2.0))
        let newFrame = CGRect(origin: newOrigin, size: newSize)
        if newFrame.width >= 100.0 && newFrame.width <= 300.0 {
            layer.borderWidth -= offset
            layer.cornerRadius += (offset / 2.0)
            layer.frame = newFrame
        }
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        setupLayer(myLayer)
        // Do any additional setup after loading the view, typically from a nib.
    }

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


}