Circular transition (mask) in iOS and Objective C

Question

We were wondering how we can easily build a circular mask, that blends out the background and transitions into a new view, with new buttons? See example here (watch the red planet gets triggered):

Answer 1

//Swift 4

This is a simple static method for circular bubble transition from a point screen.

//as shown on this link https://github.com/andreamazz/BubbleTransition

    import UIKit

    class AnimationUtility: UIViewController {
        static func animateBubbleTrnsitionView( selfView: UIView, point : CGPoint) {
                //let button = CGRect.init(x: 30, y: selfView.frame.size.height - 15, width: 45, height: 45)
                let button = CGRect.init(x: point.x, y: point.y, width: 0, height: 0)

                let circleMaskPathInitial = UIBezierPath(ovalIn: CGRect.init(x: point.x, y: point.y, width: 1, height: 1))
                let extremePoint = CGPoint(x: point.x, y: 15 - selfView.frame.size.height - 200)
                let radius = sqrt((extremePoint.x*extremePoint.x) + (extremePoint.y*extremePoint.y))
                let circleMaskPathFinal = UIBezierPath(ovalIn: (button.insetBy(dx: -radius, dy: -radius)))

                let maskLayer = CAShapeLayer()
                maskLayer.path = circleMaskPathFinal.cgPath
                selfView.layer.mask = maskLayer

                let maskLayerAnimation = CABasicAnimation(keyPath: "path")
                maskLayerAnimation.fromValue = circleMaskPathInitial.cgPath
                maskLayerAnimation.toValue = circleMaskPathFinal.cgPath
                maskLayerAnimation.duration =  0.9
                maskLayer.add(maskLayerAnimation, forKey: "path")
            }
}

Use this code in following way Perform segue or push without animation.

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
            // Get the new view controller using segue.destinationViewController.
            // Pass the selected object to the new view controller.
            switch segue.identifier! {
            case "navToHomeWithoutanimation":
                self.navigationController?.view.backgroundColor = APP_ORANGE_COLOR  //which ever color you want
                let vc = segue.destination as! MapViewController
                AnimationUtility.animateBubbleTrnsitionView(selfView: vc.view, point: self.view.center)
                break
    }
   }

//The animation will start to animate from given point.

Answer 2

Swift code :

I writted all code appdelegate file. Used a screenshot of timeline rather than a full-blown UITableView.

First, let’s add the screenshot on the window:

let imageView = UIImageView(frame: self.window!.frame)
imageView.image = UIImage(named: "twitterscreen")
self.window!.addSubview(imageView)


self.mask = CALayer()
self.mask!.contents = UIImage(named: "twitter logo mask").CGImage
self.mask!.bounds = CGRect(x: 0, y: 0, width: 100, height: 100)
self.mask!.anchorPoint = CGPoint(x: 0.5, y: 0.5)
self.mask!.position = CGPoint(x: imageView.frame.size.width/2, y: imageView.frame.size.height/2)
imageView.layer.mask = mask

animating the mask. You’ll observe that the bird reduces in size for a bit, and then increases in size, so to do that using just one animation, let’s use CAKeyframeAnimation.

let keyFrameAnimation = CAKeyframeAnimation(keyPath: "bounds")
keyFrameAnimation.duration = 1
keyFrameAnimation.timingFunctions = [CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut), CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)]
let initalBounds = NSValue(CGRect: mask!.bounds)
let secondBounds = NSValue(CGRect: CGRect(x: 0, y: 0, width: 90, height: 90))
let finalBounds = NSValue(CGRect: CGRect(x: 0, y: 0, width: 1500, height: 1500))
keyFrameAnimation.values = [initalBounds, secondBounds, finalBounds]
keyFrameAnimation.keyTimes = [0, 0.3, 1]
self.mask!.addAnimation(keyFrameAnimation, forKey: "bounds")

If you see result please visit the github repo. https://github.com/rounak/TwitterBirdAnimation/