MGLMapView turns black when returning from another UIViewController.

[mb12]

This consistently reproduces. Here is how to reproduce it.

1. From the UIViewController that hold MGLMapView push a new UIViewController
2. Tap Back

Screen is black after tapping back.

This is what I have tried to figure out the root cause so far. Please note #2 (Issue disappears when breakpoint inserted inside asyncRender callback function).

1.) I tried forcing rerender via Map::update from viewWillAppear (UIThread) but it does not seem to help.
2.) If I put breakpoint inside asyncRender to debug whether the render is actually happening, the issue disappears.

[robipresotto]

+1

[incanus]

@kkaefer Do you think this might be related to your recent missing frame fix?

@mb12 @robipresotto Can you see if the situation changes without 47ede85, which fixed the above issue recently?

[mb12]

@incanus Forcing rerender via Map::update from UIViewController::viewDidAppear addresses the issue. I will keep an eye on it and let you know if the issue reappears with this change. I think this also explains why putting breakpoint in asyncRender was causing the issue to disappear.

When I had it in viewWillAppear, it wasn't helping until I put a breakpoint in asyncRender. Putting breakPoint in asyncRender was probably forcing render to happen after viewDidAppear.

[robipresotto]

[[MGLMapView alloc] initWithFrame: styleJSON: accessToken:];

I receive this error when the user go out of the app and back to the app,
[ERROR] Setup: (-1) loading style failed: The operation couldn’t be completed. (NSURLErrorDomain error -1002.)

The error turns the map view black in my case

ideas?

[robipresotto]

The StyleURL from this method is empty when you close the app and re-open the app (or push the mapviewcontroller from another view)...

void Map::prepare() {
assert(std::this_thread::get_id() == mapThread);

if (!style) {
    style = std::make_shared<Style>();

    env->request({ Resource::Kind::JSON, styleURL}, [&](const Response &res) {
        if (res.status == Response::Successful) {
            // Calculate the base
            const size_t pos = styleURL.rfind('/');
            std::string base = "";
            if (pos != std::string::npos) {
                base = styleURL.substr(0, pos + 1);
            }

            setStyleJSON(res.data, base);
        } else {
            Log::Error(Event::Setup, "loading style failed: %s", res.message.c_str());
            std::cout << "styleURL " << styleURL;
        }
    });
}

[robipresotto]

@mb12 how are you updating the map from uiviewcontroller? for me still the same problem...

[incanus]

@mb12 @robipresotto How is this looking to you currently on master?

[mb12]

I think the issue that I've reported and the one @robipresotto is referring to are different issues.
I can try the latest master tomorrow morning or on Monday but I don't think the issue is fixed since its related to UIViewController lifecycle.

1.) From MBXViewController, push/present an new UIViewController.
2.) Tap on "Back".

The MapScreen turns black unless touched / re-rendered. I am able to work around it by forcing re-render from viewDidAppear.

[robipresotto]

okay, can be! i can open a new issue.

[1ec5]

Doesn’t currently seem to reproduce with push or show segues in storyboards. Let’s see if it reproduces programmatically…

[1ec5]

@mb12, I still can’t reproduce the issue on master (iOS 8.3 iPhone 6 Simulator, iOS 8.2 iPhone 5 Simulator, iOS 8.2 iPhone 6):

Can you share the code you’re working with?

[mb12]

Sorry I misunderstood your question.
The only difference is that I've everything inside a UINavigationController.

1. MBXViewController is the root controller in the navigation UINavigationController stack.

I've updated to the latest repo. Let me try by commenting the call to triggerUpdate in viewDidAppear.

[mb12]

This bug is fixed in the latest repo. Latest MGLMapView uses drawInRect to call renderSync from drawInRect:.
I've an old repo where the bug reproduces because renderSync in missing from drawInRect:.

Thank you very much for following up on this and fixing it properly.

[1ec5]

Glad to hear it’s working now!