HeroTransition

A UIKit implementation of a hero image transition between view controllers, using a snapshot-based animation technique.

Overview

HeroAnimator conforms to UIViewControllerAnimatedTransitioning and produces a smooth "shared element" transition. It captures a snapshot of the source image view, flies it across the screen to the destination frame using spring physics, and reveals the destination view controller underneath.

Features

• Shared-element hero transition for UIImageView
• Snapshot-based animation (no view hierarchy hacking)
• Spring animation with damping 0.9 and initial velocity 1.6 for a natural feel
• Animates both frame, corner radius, and alpha simultaneously
• Views are tagged (tag 100) for easy source/destination lookup
• 0.3 s transition duration

Tech Stack

• Swift — UIKit, UIViewControllerAnimatedTransitioning
• UIKit — UIView.animate(withDuration:usingSpringWithDamping:...)

Requirements

• Xcode 14+
• iOS 15+

Usage

1. Add HeroAnimator.swift to your project.
2. Tag the source UIImageView and the destination UIImageView both with tag 100.
3. Return a HeroAnimator instance from your UINavigationControllerDelegate or UIViewControllerTransitioningDelegate:

func animationController(forPresented presented: UIViewController,
                         presenting: UIViewController,
                         source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    return HeroAnimator(imageView: selectedImageView)
}

License

Apache License 2.0 — see LICENSE for details.