Wait for Swift animation to complete before executing code

You can use a CATransaction to call a completion block after the animation completes.

func shakeView(iv: UIImageView){

    CATransaction.begin()
    CATransaction.setCompletionBlock({
        iv.hidden = true
    })
    var shake:CABasicAnimation = CABasicAnimation(keyPath: "position")
    shake.duration = 0.1
    shake.repeatCount = 21
    shake.autoreverses = true

    var from_point:CGPoint = CGPointMake(iv.center.x - 5, iv.center.y)
    var from_value:NSValue = NSValue(CGPoint: from_point)

    var to_point:CGPoint = CGPointMake(iv.center.x + 5, iv.center.y)
    var to_value:NSValue = NSValue(CGPoint: to_point)

    shake.fromValue = from_value
    shake.toValue = to_value
    iv.layer.addAnimation(shake, forKey: "position")
    CATransaction.commit()
}

Or you can also group both animations together in a CATransaction as follows.

func shakeView(iv: UIImageView){
    var shake:CABasicAnimation = CABasicAnimation(keyPath: "position")
    shake.duration = 0.1
    shake.repeatCount = 21
    shake.autoreverses = true

    var from_point:CGPoint = CGPointMake(iv.center.x - 5, iv.center.y)
    var from_value:NSValue = NSValue(CGPoint: from_point)

    var to_point:CGPoint = CGPointMake(iv.center.x + 5, iv.center.y)
    var to_value:NSValue = NSValue(CGPoint: to_point)

    shake.fromValue = from_value
    shake.toValue = to_value
    iv.layer.addAnimation(shake, forKey: "position")
}

override func viewDidLoad() {
    CATransaction.begin()

    CATransaction.setCompletionBlock({
        self.image1.hidden = true
        self.image2.hidden = true
    })
    shakeView(image1)
    shakeView(image)
  CATransaction.commit()
}