Properly wait for dismissal before presenting a new view controller

[ChronicLynx]

First time contributor checklist

• I have read the README and CONTRIBUTING documents
• I have signed the Contributor Licence Agreement

Contributor checklist

• My commits are rebased on the latest main branch
• My commits are in nice logical chunks
• My contribution is fully baked and is ready to be merged as is
• I have tested my contribution on these devices:

• iPhone 16 Pro (Xcode Simulator - 18.2)

---

Description

Potentially fixes #5976

My theory, given the error in #5976, is that because the original code failed to wait for the dismissal to complete, it would occasionally try to present a new view while an existing view was present. This caused the animation for the navigation buttons in ImageEditorCropViewController and similar image editing views to be left in a state with no bottom navigation buttons. Therefore, the user has to force quit the app in order to exit the view. I think this may stabilize that flow and prevent such situations from occurring.

ImageEditorCropViewController:

I would imagine when encountering the error

2025/02/20 00:54:25:091 ERR❤️ [AttachmentPrepViewController.swift:221 presentFullScreen(viewController:)]: Already has presented view controller. [<SignalUI.ImageEditorCropViewController: 0x127aef700>

that it possibly short circuits or resets the logic responsible for summoning the bottom buttons. I was originally fixated on the logic summoning the buttons until I noticed a seemingly correlated error with the occurrence of the bug in AttachmentPrepViewController.

override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        transitionUI(toState: .final, animated: true)
    }

private func transitionUI(toState state: UIState, animated: Bool, completion: ((Bool) -> Void)? = nil) {
        let layoutGuide: UILayoutGuide = {
            switch state {
            case .initial: return initialStateContentLayoutGuide
            case .final: return finalStateContentLayoutGuide
            }
        }()

        let hideControls = state == .initial
        let setControlsHiddenBlock = {
            let alpha: CGFloat = hideControls ? 0 : 1
            self.footerView.alpha = alpha
            self.cropView.setState(state == .initial ? .initial : .normal, animated: false)
            self.bottomBar.setControls(hidden: hideControls)
        }

        let animationDuration: TimeInterval = 0.15

        let imageCornerRadius: CGFloat = state == .initial ? ImageEditorView.defaultCornerRadius : 0
        if animated {
            let animation = CABasicAnimation(keyPath: #keyPath(CALayer.cornerRadius))
            animation.fromValue = imageView.layer.cornerRadius
            animation.toValue = imageCornerRadius
            animation.duration = animationDuration
            imageView.layer.add(animation, forKey: "cornerRadius")
        }
        imageView.layer.cornerRadius = imageCornerRadius

        if animated {
            UIView.animate(withDuration: animationDuration,
                           animations: {
                setControlsHiddenBlock()
                self.constrainContent(to: layoutGuide)
                self.updateImageViewTransform()
                // Animate layout changes made within bottomBar.setControls(hidden:).
                self.view.setNeedsDisplay()
                self.view.layoutIfNeeded()
            },
                           completion: completion)
        } else {
            setControlsHiddenBlock()
            constrainContent(to: layoutGuide)
            updateImageViewTransform()
            completion?(true)
        }
    }

[sashaweiss-signal]

Especially since this isn't related to the fix, I'm more inclined to drop the viewController.modalPresentationStyle = .fullScreen here, and continue to call self.presentFullScreen here.

[sashaweiss-signal]

I'm not sure that this will fix the linked issues, but it seems like a reasonable change nonetheless. I can get this merged internally (and I can make the adjustment I left a comment about, while I'm there).

Our flow for external contributions is to recreate the diff internally, and commit it using the external author's information. Would you mind emailing me at [email protected] with a name and email you'd like used in the commit authorship? Thank you!

[sashaweiss-signal]

This was merged internally as d7e9a88, which should become public tomorrow with our upcoming release! Thanks for the contribution.