Add wiggle animation to UIButton

UIButtonXT.swift

import UIKit

extension UIButton {
  	// Animate a button, adding effect of "something went wrong". Useful for login button for example.
	func wiggle() {
		let wiggleAnim = CABasicAnimation(keyPath: "position")
		wiggleAnim.duration = 0.05
		wiggleAnim.repeatCount = 5
		wiggleAnim.autoreverses = true
		wiggleAnim.fromValue = CGPoint(x: self.center.x - 4.0, y: self.center.y)
		wiggleAnim.toValue = CGPoint(: self.center.x + 4.0, y: self.center.y)
		layer.add(wiggleAnim, forKey: "position")
	}
}