Resizing an UIImageView via UIViewPropertyAnimator makes loaded image disappear and placeholder appear

[m4p]

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Issue Description

What

Resizing an UIImageView via UIViewPropertyAnimator makes loaded image disappear and placeholder appear. Only happens when image is not cached. I'm attaching sample code and a screen recording.

Reproduce

//
//  ViewController.swift
//  KingFisherResizing
//
//  Created by Martin Pittenauer on 16.02.24.
//

import UIKit
import Kingfisher

class ViewController: UIViewController {

    private lazy var imageView: UIImageView = {
        let imageView = UIImageView()
        imageView.translatesAutoresizingMaskIntoConstraints = false
        imageView.contentMode = .scaleAspectFill
        imageView.clipsToBounds = true
        return imageView
    }()

    lazy var widthConstraint: NSLayoutConstraint = { imageView.widthAnchor.constraint(equalToConstant: 200)
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        view.addSubview(imageView)
        NSLayoutConstraint.activate([
            imageView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            imageView.topAnchor.constraint(equalTo: view.topAnchor),
            imageView.heightAnchor.constraint(equalTo: imageView.widthAnchor, multiplier: 9/16),
            widthConstraint
        ])

        let imageUrl = URL(string: "https://res.cloudinary.com/dg-stage/image/fetch/w_2642/https://dg-stage-production-pictures.s3.eu-west-1.amazonaws.com/be9e66cd3f8fc57d008b5969ad87ce04c385bbbe.jpg?_a=AEABoAB0")!
        let placeholder = UIImage(named: "placeholder")
        
        imageView.kf.setImage(with: imageUrl, placeholder: placeholder, options: [.transition(.fade(0.4)), .forceRefresh])
        
        startTimer()
    }

    var fraction: Double = 0.0
    var change: Double = 0.02
    var timer: Timer?
    var animator: UIViewPropertyAnimator?

    func startTimer() {
        widthConstraint.constant = 900
        animator = UIViewPropertyAnimator(duration: 1.0, curve: .easeInOut) { [weak self] in
            self?.view.layoutIfNeeded()
        }
        animator?
            .pauseAnimation()


        timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [weak self] _ in
            guard let self else { return }
            if self.fraction <= 0 {
                change = 0.02
            }
            if self.fraction >= 1 {
                change = -0.02
            }
            
            self.fraction = self.fraction + change
            animator?.fractionComplete = self.fraction
        }
    }
}

[m4p]

This is caused by the UIView.transition used by Kingfisher in makeTransition() still being part of the UIImageView and being triggered in reverse. It needs to be removed after it is finished. Unfortunately it seems UIViewPropertyAnimator captures it and prevents it from being removed automatically.

A hacky workaround that seems to work is:

        imageView.kf.setImage(with: imageUrl, placeholder: placeholder, options: [.transition(.fade(0.4)), .forceRefresh, .waitForCache]) { _ in
            if let keys = self.layer.animationKeys(), keys.contains("contents") {
                self.imageView.layer.removeAnimation(forKey: "contents")
            }
        }

[onevcat]

Ummm...

I used the sample code to try to reproduce the issue, but was unsuccessful. There may be other factors causing the problem...

Simulator.Screen.Recording.-.iPhone.8.-.2024-02-18.at.16.18.49.mp4

[m4p]

Here's the complete reproduction Xcode project:
samplecode.zip
I'm using Xcode 15.2 and the iPad (10th gen) simulator.