How can I achieve a smooth animation when dragging a UIView - ios

Question

This is the code I have written so far to change the position of the view when dragged.
The view changes its center point when the UIPanGestureRecognizer is either changed or began and that happen when I let go the gesture. I do not want that. I want it to go along with my drag like what the Notification Center and Control Center does.
Thanks in advance for the help.
class ViewController: UIViewController {
let maxY = UIScreen.main.bounds.height
lazy var slideUpView: UIView = {
let view = UIView(frame: CGRect(x: 0, y: maxY - 295, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height / 3 ))
view.backgroundColor = .green
return view
}()
lazy var redImageView: UIView = {
let view = UIView(frame: CGRect(x: 0, y: maxY - 295, width: UIScreen.main.bounds.width, height: slideUpView.frame.height / 2 ))
view.backgroundColor = .red
return view
}()
override func viewDidLoad() {
super.viewDidLoad()
print("MaxX: \(UIScreen.main.bounds.maxX)")
print("Max Hight: \(UIScreen.main.bounds.height)")
print("MaxY: \(UIScreen.main.bounds.maxY)")
print("Max width: \(UIScreen.main.bounds.width)")
// MARK: add the views as subview
let viewsArray = [slideUpView, redImageView]
viewsArray.forEach{view.addSubview($0)}
// Add a UIPanGestureRecognizer to it
viewsArray.forEach {createPanGestureRecognizer(targetView: $0)}
}
// The Pan Gesture
func createPanGestureRecognizer(targetView: UIView) {
let panGesture = UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture(recognizer:)))
panGesture.maximumNumberOfTouches = 1
targetView.addGestureRecognizer(panGesture)
}
#objc func handlePanGesture(recognizer: UIPanGestureRecognizer) {
if recognizer.state == UIGestureRecognizerState.began || recognizer.state == UIGestureRecognizerState.changed {
let translation = recognizer.translation(in: self.view)
print(recognizer.view!.center.y)
let newPos = CGPoint(x:recognizer.view!.center.x + translation.x, y: recognizer.view!.center.y + translation.y)
if insideDraggableArea(newPos) {
guard let targetedView = recognizer.view else {
print("Error: No View to handle")
return
}
targetedView.center.y = newPos.y
recognizer.setTranslation(.zero, in: targetedView)
}
}
}
private func insideDraggableArea(_ point : CGPoint) -> Bool {
return // point.x > 50 && point.x < 200 &&
point.y > (maxY * 0.27) && point.y <= maxY
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
let position = touch.location(in: view)
print(position)
}
}
}

Answer 1

I also had this issue, at least in a playgrounds prototype...
I put all of the translation (that you have in the changed state) inside of a UIViewProperty animator that I had defined within the handlePanGesture function and then called .startAnimation() within the began/changed state.
It takes a bit of tweaking on the animation but its a lot smoother for me..

Answer 2

This code works fine. The issues was in the simulator I used yesterday. Everything works as I wanted it to be when tested in an iPhone.