Snapchatのボタンみたいにタップ中に大きくなるUIButtonの作り方

SnapChatみたいにフォーカス中だけ大きくなるUIButtonができたのでシェアします。

.touchDown で大きくして、.touchUpInside, .touchUpOutside, .touchCancel で小さくします。

IBActionでタップイベントを定義せずに、

button.setOnClickListener {[weak self] in
    self?.thinkUnique()
}

みたいな感じで使います。

import UIKit

class MicroInteractButton: UIButton {
    private var clickListener: (() -> Void)?

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        setupAnimation()
        adjustsImageWhenHighlighted = false
    }

    func setOnClickListener(_ completion: (() -> Void)?) {
        clickListener = completion
    }

    private func setupAnimation(){
        addTarget(self, action: #selector(pressed), for: [.touchDown])
        addTarget(self, action: #selector(released), for: [.touchUpInside, .touchUpOutside, .touchCancel])
    }

    @objc private func pressed(){
        expandAnimation()
    }

    @objc private func released(){
        shrinkAnimation()

        DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
            self.clickListener?()
        }
    }

    private func expandAnimation() {
        let expand = CASpringAnimation(keyPath: "transform.scale")
        expand.duration = 0.2
        expand.fromValue = 1
        expand.toValue = 1.3
        expand.autoreverses = false
        expand.repeatCount = 1
        expand.initialVelocity = 0.8
        expand.damping = 1.0
        expand.fillMode = kCAFillModeForwards
        expand.isRemovedOnCompletion = false
        layer.bounds = self.bounds
        layer.contentsGravity = "center"
        layer.add(expand, forKey: "expand")
    }

    private func shrinkAnimation() {
        let shrink = CABasicAnimation(keyPath: "transform.scale")
        shrink.duration = 0.2
        shrink.fromValue = 1.3
        shrink.toValue = 1
        shrink.autoreverses = false
        shrink.repeatCount = 1
        shrink.fillMode = kCAFillModeForwards
        shrink.isRemovedOnCompletion = false
        layer.add(shrink, forKey: "shrink")
    }
}

gistにあげてます。
https://gist.github.com/kboy-silvergym/62de6540ee61d879ca584e707719e171