Hello,
I’m developing an app where I display a SwiftUI view inside a UIHostingController embedded within a UIKit ViewController. I’m trying to animate the height of the UIHostingController’s view based on a switch’s value, but the SwiftUI view doesn’t animate at all.
Below is a simplified version of my code:
class ViewController: UIViewController { private lazy var parentView: UIView = { let view = UIView() view.backgroundColor = .red view.translatesAutoresizingMaskIntoConstraints = false return view }() private lazy var hostingView: UIView = { let testView = TestView() let hostingController = UIHostingController(rootView: testView) let view = hostingController.view! view.translatesAutoresizingMaskIntoConstraints = false return view }() private lazy var button: UISwitch = { let button = UISwitch() button.addTarget(self, action: #selector(onClickSwitch(sender:)), for: .valueChanged) button.translatesAutoresizingMaskIntoConstraints = false return button }() private var hostingViewHeightConstraint: NSLayoutConstraint? override func viewDidLoad() { super.viewDidLoad() view.addSubview(parentView) parentView.addSubview(hostingView) parentView.addSubview(button) NSLayoutConstraint.activate([ parentView.topAnchor.constraint(equalTo: view.topAnchor), parentView.bottomAnchor.constraint(equalTo: view.bottomAnchor), parentView.leadingAnchor.constraint(equalTo: view.leadingAnchor), parentView.trailingAnchor.constraint(equalTo: view.trailingAnchor) ]) NSLayoutConstraint.activate([ hostingView.bottomAnchor.constraint(equalTo: parentView.bottomAnchor), hostingView.leadingAnchor.constraint(equalTo: parentView.leadingAnchor), hostingView.trailingAnchor.constraint(equalTo: parentView.trailingAnchor) ]) hostingViewHeightConstraint = hostingView.heightAnchor.constraint(equalTo: parentView.heightAnchor, multiplier: 0.5) hostingViewHeightConstraint?.isActive = true NSLayoutConstraint.activate([ button.centerXAnchor.constraint(equalTo: parentView.centerXAnchor), NSLayoutConstraint(item: button, attribute: .centerY, relatedBy: .equal, toItem: parentView, attribute: .centerY, multiplier: 0.25, constant: 0) ]) } @objc func onClickSwitch(sender: UISwitch) { hostingViewHeightConstraint?.isActive = false let multiplier: CGFloat = sender.isOn ? 0.25 : 0.5 hostingViewHeightConstraint = hostingView.heightAnchor.constraint(equalTo: parentView.heightAnchor, multiplier: multiplier) hostingViewHeightConstraint?.isActive = true UIView.animate(withDuration: 0.3) { self.view.layoutIfNeeded() } } }
I’m looking for the behavior demonstrated in the video below:
Does anyone have suggestions on how to achieve this?