Moving UIImage Up and Down with Animation in Swift - ios

Question

I have just recently started with Xcode and Swift and I am trying to get my image to move up and down and have it switch directions when the user taps the screen. My image just will not move at all and the app will either crash or just freeze.
import UIKit
import SpriteKit
import Darwin
let startButton = UIButton(frame: CGRect(x: 200, y: 100, width: 100, height: 50))
let screenSize = UIScreen.main.bounds
let gameButton = UIButton(frame: CGRect(x: 0, y: 0, width: screenSize.width, height: screenSize.height))
var dot: UIImage = UIImage(named: "dot")!
var dotPic = UIImageView(image: dot)
public var goingUp = true
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = .white
startButton.addTarget(self, action: #selector(startButtonAction), for: .touchUpInside)
startButton.setImage(UIImage.init(named: "startButton"), for: .normal)
self.view.addSubview(startButton)
}
func startButtonAction(sender: UIButton!) {
print("button clicked")
startButton.isEnabled = false
startButton.setImage(UIImage.init(named: "nothing"), for: .normal)
self.view.backgroundColor = .gray
dotPic.frame = CGRect(x: 50, y: 300, width: 20, height: 20)
self.view.addSubview(dotPic)
self.view.addSubview(gameButton)
playGame()
}
func playGame(){
gameButton.addTarget(self, action: #selector(gameButtonAction), for: .touchUpInside)
gameButton.setImage(UIImage.init(named: "nothing"), for: .normal)
}
func gameButtonAction(sender: UIButton!) {
goingUp = !goingUp
print(goingUp)
print("clicked up/down")
func rep(){
repeat{
dotPic.frame = CGRect(x: 50, y: 300-1, width: 20, height: 20)
sleep(UInt32(0.3))
}while goingUp==true
repeat{
dotPic.frame = CGRect(x: 50, y: 300-1, width: 20, height: 20)
sleep(UInt32(0.3))
}while goingUp==false
}
rep()
}
}
I have tried using animateWithDuration() too but it has always frozen the app. What am I doing wrong?

Answer 1

Tried to use this code in swift...
self.hintImageView.frame = CGRect(x: x, y: 55, width: 200, height: 40)
UIView.animate(withDuration: 0.5, delay: 0, options: [.repeat, .autoreverse] , animations: {
self.hintImageView.frame = CGRect(x: x, y: 65, width: 200, height: 40);
}) { (completed) in
}

Answer 2

Here, Try this, instead of func rep() in your gameButtonAction :
[UIView animateWithDuration:duration delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
//code with animation
dotPic.frame = CGRect(x: 50, y: 300-1, width: 20, height: 20)
} completion:^(BOOL finished) {
//code for completion
dotPic.frame = CGRect(x: 50, y: 300, width: 20, height: 20)
}];
and avoid using nested function rep() in your target. Probably it is running continuously causing your application to hang.