fix: Call UI not maximizing after account switch - WPB-20468

[KaterinaWire]

WPB-20468 [iOS] Accepting call on 2nd account doesn't open calling UI but only show green banner on top with connected timer in the conversation

Issue

When receiving a call on an inactive account, the app switches to the correct account, but only shows the green top bar.

From the UI perspective the flow is

1. Receiving an incoming call on an inactive account and tapping the CallKit notification
2. App opens and switches to the inactive account
3. Calling UI briefly appears showing "Connecting..." state
4. Calling UI is dismissed/covered when conversation view appears
5. User sees only the conversation without the calling UI overlay

The calling UI is shown before the conversation navigation completes, and then the conversation appearing dismisses the calling UI.

func showConversation(
        _ conversation: ZMConversation,
        at message: ZMConversationMessage? = nil,
        in session: ZMUserSession
    ) {
        guard !conversation.isDeletedRemotely else {
            return
        }

        activateAccount(for: session) {
            self.presentationDelegate?.showConversation(conversation, at: message)
        }
    }

updateActiveCallPresentationState() is called inside the loadSession flow (activateAccount ->select() -> loadSession ) before the completion executes to show the conversation. The conversation navigation then interferes with the already shown calling UI.

Solution

Display the calling UI after the conversation is fully visible.

1. Post notification when conversation view appears.
2. Observe notification in SessionManager.activateAccount() and triggers updateActiveCallPresentationState() at the right time - after conversation is visible

Testing

• Receive call on inactive account → ✅ Switches account and shows full call UI immediately

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Checklist

• Title contains a reference JIRA issue number like [WPB-XXX].
• Description is filled and free of optional paragraphs.
• Adds/updates automated tests.

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UI accessibility checklist

If your PR includes UI changes, please utilize this checklist:

• Make sure you use the API for UI elements that support large fonts.
• All colors are taken from WireDesign.ColorTheme or constructed using WireDesign.BaseColorPalette.
• New UI elements have Accessibility strings for VoiceOver.

[github-actions]

Test Results

3 166 tests   3 139 ✅  3m 55s ⏱️
  450 suites     27 💤
    2 files        0 ❌

Results for commit 9e9282c.

♻️ This comment has been updated with latest results.

[johnxnguyen]

question: can we move this inside the user session? The session manager shouldn't be concerned about this so it'd be good to avoid it if possible.

[KaterinaWire]

Well, I can share my thoughts on why I would prefer to keep it in SessionManager, but I'm open to your suggestions.
SessionManager owns presentationDelegate that already has API for UI communication in a context of account coordination/switching.
This is a use case specifically for switching between accounts and SessionManager orchestrating it.

[KaterinaWire]

I also moved the code around and added more comments

[johnxnguyen]

suggestion: it doesn't seem necessary to pass the conversation, perhaps you can remove it?

[KaterinaWire]

Yes, removed

[johnxnguyen]

I'm not a big fan of posting notifications like this but I understand an alternative solution must be tricky. Just so I understand, what's stopping us from awaiting the completion of showing the conversation directly? i.e something like

showConversation(completion: {
  // do something
})