uiview_animations_repeat.swift

@IBAction func buttonDidTap(_ sender: Any) {
        // Check text in field. Animation is starting only if text is empty
        if field.text?.isEmpty ?? true {
            UIView.animate(withDuration: 0.3,
                           delay: 0.0,
                           // Look options list here https://developer.apple.com/documentation/uikit/uiviewanimationoptions
                           options: [.autoreverse],
                           animations: {
                            // Create CGAffineTransform with 5 degree (CG works with radians) and convert in to radians
                            self.field.transform = CGAffineTransform(rotationAngle: CGFloat(5).degreesToRadians)
                                // Add scale factor to the created transform
                                .scaledBy(x: 1.2, y: 1.2)
            }) { (finish) in
                // Clear transform .identity is a empty transform
                self.field.transform = .identity
                print("\(String(describing: self.field)) animation finish: \(finish)")
            }
        } else {
            // Start Repeat Animation for UILabel
            UIView.animate(withDuration: 0.5,
                           delay: 0.0,
                           // .repeat option create loop for that animation
                           options: [.repeat, .autoreverse],
                           animations: {
                            // Concat static text with text from UITextField
                            self.label.text = "Entered name: " + (self.field.text ?? "")
                            // Make offset from UILabel frame
                            self.label.frame = self.label.frame.offsetBy(dx: 100, dy: 0)
            }) { (finish) in
                print("\(String(describing: self.label)) animation finish: \(finish)")
            }
        }
    }