How to change the size of the animation json Lottie framework?

You simply do not specify the size. To change the size, change the value of the size variable.

import UIKit import Lottie class ViewController: UIViewController { let animationView = AnimationView() let size: CGFloat = 500 override func viewDidLoad() { super.viewDidLoad() let animation = Animation.named("5438") animationView.animation = animation animationView.play() animationView.loopMode = .loop animationView.frame = CGRect(x: 0, y: 0, width: size, height: size) animationView.contentMode = .scaleAspectFill view.addSubview(animationView) animationView.translatesAutoresizingMaskIntoConstraints = false animationView.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor, constant: 0).isActive = true animationView.heightAnchor.constraint(equalToConstant: size).isActive = true animationView.widthAnchor.constraint(equalToConstant: size).isActive = true animationView.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true } }