Hero库转场异常：Present视图控制器无动画，Dismiss正常如何解决

Hey there! I’ve run into this exact issue with Hero before—dismiss animations working but present ones being MIA is usually a simple configuration oversight. Let’s walk through the most likely fixes:

1. Use Hero’s Present Method (Not System Default) #

First off, make sure you’re calling Hero’s dedicated present method instead of UIKit’s default present(_:animated:completion:). Hero needs to hook into the transition process, and using the system method skips that entirely:

// ❌ Wrong: Uses UIKit's default present, skips Hero
present(secondVC, animated: true, completion: nil)

// ✅ Correct: Uses Hero's present to trigger animation
hero.present(secondVC, animated: true, completion: nil)

2. Assign Hero Properties to the Presented View Controller #

Hero needs clear instructions on how to animate the transition. You can do this in two straightforward ways:

• Option A: Link views with a shared Hero ID
  If you want a seamless transition between a specific view in your source VC and the presented VC’s view, set matching hero.id values:

  // In your source VC (e.g., the button that triggers the present)
  triggerButton.hero.id = "transitionButton"
  
  // In your presented VC's viewDidLoad
  override func viewDidLoad() {
      super.viewDidLoad()
      view.hero.id = "transitionButton"
  }
  

• Option B: Set a direct modal animation type
  If you don’t need a view-linked transition, explicitly define the animation type for the presented VC:

  // In presented VC's viewDidLoad
  override func viewDidLoad() {
      super.viewDidLoad()
      view.hero.modalAnimationType = .zoom // Or .slide, .fade, .flip, etc.
  }
  

3. Check for Accidentally Disabled Hero Animations #

Double-check that you haven’t toggled off Hero functionality somewhere:

• Ensure view.hero.isEnabled = true (this is the default, but if you’ve overridden it in a base VC or global setting, reset it)
• Avoid global settings like Hero.shared.defaultAnimation = .none unless you explicitly override it for the present transition

4. Handle Navigation Controllers (If Presenting One) #

If you’re presenting a UINavigationController instead of a plain VC, apply the Hero properties to the navigation controller’s view instead of its root VC:

let navVC = UINavigationController(rootViewController: SecondViewController())
navVC.view.hero.modalAnimationType = .slide(direction: .right)
hero.present(navVC, animated: true, completion: nil)

Quick Troubleshooting Tip #

If none of the above works, add a quick print statement in your presented VC’s viewWillAppear to confirm Hero is active:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    print("Hero enabled for this VC: \(view.hero.isEnabled)")
}

9 times out of 10, the issue is forgetting to use hero.present() or not setting the correct Hero animation properties on the presented side. Give these steps a shot!

内容的提问来源于stack exchange，提问作者Phoenix