I have a container View with adjustable height. Now I want to set the same frame of the view of child view controller according to container view's height. Sometimes it does work in the simulation but often it fails. The frame of child view controller's view often stays the same as defined at the beginning. Do you know a workaround to solve this problem ?
Here is my main ViewController with containerView named bottomView
class ViewController: UIViewController {
var startPosition: CGPoint!
var originalHeight: CGFloat = 0
var bottomView = UIView()
var gestureRecognizer = UIPanGestureRecognizer()
let scrollView = UIScrollView()
let controller = EditorViewController()
override func viewDidLoad() {
self.view.backgroundColor = .white
view.addSubview(bottomView)
bottomView.translatesAutoresizingMaskIntoConstraints = false
bottomView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
bottomView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
bottomView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
bottomView.heightAnchor.constraint(equalToConstant: 100).isActive = true
bottomView.backgroundColor = .white
gestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(viewDidDragged(_:)))
bottomView.isUserInteractionEnabled = true
bottomView.addGestureRecognizer(gestureRecognizer)
// add childviewController
self.addChild(controller)
controller.view.translatesAutoresizingMaskIntoConstraints = false
controller.view.frame = bottomView.bounds
bottomView.addSubview(controller.view)
controller.view.rightAnchor.constraint(equalTo: bottomView.rightAnchor).isActive = true
controller.view.leftAnchor.constraint(equalTo: bottomView.leftAnchor).isActive = true
controller.view.bottomAnchor.constraint(equalTo: bottomView.bottomAnchor).isActive = true
controller.view.topAnchor.constraint(equalTo: bottomView.topAnchor).isActive = true
controller.didMove(toParent: self)
}
}
The childView Controller looks like this:
class EditorViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = .red
}
And in this way I change the height of container view and tried to adjust the height of child viewController, too. But it does not work.
@objc func viewDidDragged(_ sender: UIPanGestureRecognizer) {
if sender.state == .began {
startPosition = gestureRecognizer.location(in: self.view) // the postion at which PanGestue Started
originalHeight = bottomView.frame.size.height
}
if sender.state == .began || sender.state == .changed {
let endPosition = sender.location(in: self.view)
let difference = endPosition.y - startPosition.y
let newHeight = originalHeight - difference
if self.view.frame.size.height - endPosition.y < 100 {
bottomView.frame = CGRect(x: 0, y: self.view.frame.size.height - 100, width: self.view.frame.size.width, height: 100)
controller.view.frame = bottomView.bounds
} else {
bottomView.frame = CGRect(x: 0, y: self.view.frame.size.height - newHeight, width: self.view.frame.size.width, height: newHeight)
controller.view.frame = bottomView.bounds
}
}
if sender.state == .ended || sender.state == .cancelled {
//Do Something
}
}
Try using a constraint to change the height. Something like:
class ViewController: UIViewController {
...
var heightConstraint: NSLayoutConstraint?
override func viewDidLoad() {
...
heightConstraint = bottomView.heightAnchor.constraint(equalToConstant: 100)
heightConstraint?.isActive = true
....
}
@objc func viewDidDragged(_ sender: UIPanGestureRecognizer) {
...
if sender.state == .began || sender.state == .changed {
let endPosition = sender.location(in: self.view)
let difference = endPosition.y - startPosition.y
let newHeight = originalHeight - difference
if self.view.frame.size.height - endPosition.y < 100 {
heightConstraint?.constant = 100
} else {
heightConstraint?.constant = newHeight
}
}
...
}
}