animated-layout.swift

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import UIKit
import PlaygroundSupport

let view = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 400))

var test: Bool = false

class Handler: NSObject {
    @objc func onTap() {
        // how to perform an animation of the label frame according to it's content ?
        UIView.animate(withDuration: 1) {
            bottomLabel.text = test ? "Hello\nHello\nHello" : "Hello"
        }
        test = !test
    }
}

let handler = Handler()

view.addGestureRecognizer(UITapGestureRecognizer(target: handler, action: #selector(Handler.onTap)))

let bottomLabel = UILabel()
bottomLabel.backgroundColor = .green
bottomLabel.numberOfLines = 0
bottomLabel.text = "Hello"
let topLabel = UILabel()
topLabel.backgroundColor = .purple
topLabel.text = "Always top"

let stackView = UIStackView()
stackView.translatesAutoresizingMaskIntoConstraints = false
stackView.axis = .vertical
stackView.alignment = .center

stackView.addArrangedSubview(topLabel)
stackView.addArrangedSubview(bottomLabel)


view.addSubview(stackView)
view.backgroundColor = .red

NSLayoutConstraint.activate([
    stackView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
    stackView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
    stackView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
])


PlaygroundPage.current.liveView = view



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