Simple slide up animation on UIView using NSLayoutConstraints - ios

Question

I have spent a while trying to figure this out, but I just can't. There is probably something really simple I am missing here. I am trying to animate a view coming in from the bottom. This si the code I am using for the view:
private let undoView: UIView = {
let view = UIView()
view.translatesAutoresizingMaskIntoConstraints = false
view.backgroundColor = .white
view.layer.cornerRadius = 15
view.layer.shadowOffset = .zero
view.layer.shadowOpacity = 0.3
view.layer.shadowRadius = 5
view.layer.shouldRasterize = true
view.layer.rasterizationScale = UIScreen.main.scale
let button = UIButton()
button.translatesAutoresizingMaskIntoConstraints = false
button.setTitle("Undo", for: .normal)
button.titleLabel?.textAlignment = .center
button.setTitleColor(.systemBlue, for: .normal)
let buttonConstraints = [
button.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 16),
button.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -16),
button.topAnchor.constraint(equalTo: view.topAnchor, constant: 16),
button.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -16)
]
view.addSubview(button)
NSLayoutConstraint.activate(buttonConstraints)
let swipeGesture = UISwipeGestureRecognizer(target: view, action: #selector(undoViewSwiped))
view.addGestureRecognizer(swipeGesture)
return view
}()
And this is the code I am using to try and achieve the animation:
func addUndoView() {
var bottomConstraint = undoView.topAnchor.constraint(equalTo: view.bottomAnchor, constant: 0)
let constraints = [
undoView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
undoView.widthAnchor.constraint(equalToConstant: view.bounds.width / 3),
bottomConstraint,
undoView.heightAnchor.constraint(equalToConstant: 50)
]
view.addSubview(undoView)
NSLayoutConstraint.activate(constraints)
undoView.layoutIfNeeded()
bottomConstraint.isActive = false
bottomConstraint = undoView.topAnchor.constraint(equalTo: view.layoutMarginsGuide.bottomAnchor, constant: -58)
bottomConstraint.isActive = true
UIView.animate(withDuration: 0.5, delay: 0.2, animations: {
self.undoView.layoutIfNeeded()
})
}
I want the view to just be created underneath the visible view, and then slide up to 8 above the bottom layout margin. This code however just makes the view 'expand' at its final position instead of coming into view from the bottom. Using self.view.layoutIfNeeded() makes the view fly in from the top left of the screen, for some reason.

Answer 1

good day I usually work with transform property for move one view from x position to y portion, please check this example.
class ViewController: UIViewController {
let button : UIButton = {
let button = UIButton(type: .custom)
button.setTitle("Button", for: .normal)
button.backgroundColor = .gray
button.translatesAutoresizingMaskIntoConstraints = false
return button
}()
let customView : UIView = {
let view = UIView()
view.translatesAutoresizingMaskIntoConstraints = false
view.backgroundColor = .red
return view
}()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
view.addSubview(button)
view.addSubview(customView)
NSLayoutConstraint.activate([
button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor),
button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),
customView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor),
customView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),
customView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
customView.heightAnchor.constraint(equalToConstant: 100)
])
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
setupAnimationCustomView()
}
private func setupAnimationCustomView(){
UIView.animate(withDuration: 1, delay: 0 , options: .curveEaseOut, animations: {
print(self.button.frame.origin.y)
let translationY = self.view.frame.height - self.button.frame.origin.y - self.button.frame.height - self.customView.frame.height - 8
self.customView.transform = CGAffineTransform(translationX: 0, y: translationY * (-1))
}, completion: nil)
}
}
on the animation I calculate the distance that I need to move my customView.