floatingPanelDidMove not triggered when moving to/from hidden state

[fawzirifai]

When moving the panel to or from the .hidden state, the floatingPanelDidMove delegate method does not trigger continuously during the transition. Instead, it only fires once after the transition completes.

Expected Behavior:
floatingPanelDidMove should be called continuously while the panel is moving between states, including when transitioning to or from .hidden.

[fawzirifai]

@scenee any update here please?

[scenee]

Sorry for the delayed response. This is the expected behavior. FloatingPanel uses UIViewPropertyAnimator when it appears or disappears from the .hidden state. The method func floatingPanelDidChangeState(_ fpc: FloatingPanelController)　might help you control views alongside the panel during these transitions.

Moreover, you can define a custom state as a replacement for .hidden and simply use
move(to: FloatingPanelState, animated: Bool, completion: (() -> Void)? = nil)
to show or hide a panel from that state.

[fawzirifai]

didChangeState also triggers once, I want a method to trigger on each frame change while the floating panel is presenting or dismissing.

Defining a custom state will not help me also, since I use present and removePanel methods to present and dismiss the panel, and these methods moves the panel from .hidden and to .hidden state.

@scenee

[fawzirifai]

Any update please? @scenee

[scenee]

Could you elaborate on what you're trying to achieve with floatingPanelDidMove during presenting/dismissing transitions? If you want to animate other views alongside the panel, you can use the delegate methods that return a UIViewPropertyAnimator:

  func floatingPanel(_ fpc: FloatingPanelController, animatorForPresentingTo state: FloatingPanelState) -> UIViewPropertyAnimator {
      let animator = UIViewPropertyAnimator(duration: 0.25, dampingRatio: 1.0)
      animator.addAnimations {
          // Animate your views alongside the panel presentation
          self.someView.alpha = 1.0
      }
      return animator
  }

  func floatingPanel(_ fpc: FloatingPanelController, animatorForDismissingWith velocity: CGVector) -> UIViewPropertyAnimator {
      let animator = UIViewPropertyAnimator(duration: 0.25, dampingRatio: 1.0)
      animator.addAnimations {
          // Animate your views alongside the panel dismissal
          self.someView.alpha = 0.0
      }
      return animator
  }

This way you don't need per-frame callbacks — the animations run in sync with the panel transition automatically.

If this doesn't cover your use case, could you describe more specifically what you need to do on each frame during the transition?

[fawzirifai]

Thanks! What I need is continuous, per-frame updates of the panel’s position during presenting and dismissing transitions (when using addPanel / removePanel), so I can synchronize another system that depends on the panel’s exact Y position (e.g. updating layout or another component based on the panel’s frame as it animates).

Using:

animator.addAnimations { ... }

only executes the animation block once as part of the transition, and doesn’t expose intermediate values of the panel’s position over time.

floatingPanelDidMove also only fires once for addPanel and removePanel, since there’s no interactive dragging involved.

So the missing piece for my use case is a way to observe the panel’s position (or transition progress) continuously during presenting/dismissing animations, not just at the start or end.

Happy to clarify further if needed, and thanks for maintaining the library, it’s been great to work with. @scenee