Observe UIView frame while animating

Question

I have multiple UIViews that are dependant on each other, a UIView can change its frame.

Other UIViews respond accordingly to the currently changing UIView.

however, a UIView changes its frame with animations, I tried to observe a UIView's frame property but it gives me the last result after it starts animating.

Here's my current setup:

override func viewDidLoad() {
    super.viewDidLoad()

    view.addObserver(self, forKeyPath: "frame", options: [NSKeyValueObservingOptions.old, .new, .prior, .initial], context: nil)

}

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {

    if let obj = object as? UIView {
        print(obj.layer.frame.minY)
    }
}

Example of the result when I observed the obj.layer.frame.minY:

622.0
252.0

My problem is:

I want to observe the current obj.layer.frame.minY while animating.

Update:

I tried to use the presentation() method, but I still get the same result. Here's how I do it:

override func viewDidLoad() {
    super.viewDidLoad()

    view.addObserver(self, forKeyPath: "frame", options: NSKeyValueObservingOptions.new, context: nil)
}

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
//        print("value of \(keyPath) changed: \(change![NSKeyValueChangeKey.newKey])")

    if let obj = object as? UIView {
        guard let presentation = obj.layer.presentation() else { return }
        let a = presentation
        print(a)

    }

}