Setting styleURL immediately after initialization sometimes fails

[tmpsantos]

Sometimes when I start my app (iOS) with Mapbox in it, it won't load the styles into the map. It generates the default MapKit styled map, without any markers. It's kind of annoying, because the problem is somewhat occurring on a random base.

I load my custom stylesheet as a JSON file and link it to the map via the style url:

mapView?.styleURL = NSURL(string: "asset://\(jsonFile)")

Is it a known issue?

[1ec5]

Possibly related: #1208, #1279, although those issues reproduce consistently.

Where do you set styleURL? Right after initializing the MGLMapView in -viewDidLoad, or somewhere else? Does the issue reproduce if you initialize the map view with -initWithFrame:styleURL:?

[leandersikma]

It looks like #1208 is about a wrong file path to the local style URL. My styleURL is actually working and loading, but once in 20 times (or another random number) that you open the app. The style got not applied to map.

View with layout:

View with the default layout (hops in sometimes)

I'm trying -initWithFrame:styleURL: now. I have to say that the last 20 times I built/started my app, the problem didn't occur. So maybe this one is a little bit more 'stable'.

[picciano]

I've been meaning to log this. We are seeing this quite often as well.
It happens about 80% of the time with a new build though iTunesConnect/TestFlight. User must force quit, restart app, then markers appear. But I see this running directly from Xcode as well.

This is definitely a real issue. And is annoying as mentioned above.

[1ec5]

@picciano, if you’re also initializing and setting the style in separate steps, rather than using -initWithFrame:styleURL:, there may be a race condition because initialization asynchronously fetches the style and tiles. #1488 is probably playing a part in this as well: setting the styleURL separately in -viewDidLoad means you’re switching styles, which causes annotations to “disappear” before they ever get a chance to appear.

[picciano]

I'll try that and report back in a couple days. So far, so good.

[picciano]

Using using -initWithFrame:styleURL: seems to be a good work around for setting the style. I have not seen anymore missing markers by doing this.

[1ec5]

Glad to hear it works. Unfortunately, both -initWithFrame:style: and -initWithCoder: (for storyboards) rely on setting styleURL immediately after calling -commonInit. So if there’s a race condition, this only makes it less likely to present itself.

[1ec5]

Actually, -initWithFrame:styleURL: should be fine, because styleURL is only ever set once. But -initWithCoder: (again, important for storyboards) does suffer from the same problem as -initWithFrame:, because styleURL ultimately gets set more than once.

[kkaefer]

Is this possibly fixed by #1802?

[jfirebaugh]

@tmpsantos Can you investigate and determine if this is fixed?

[tmpsantos]

@tmpsantos Can you investigate and determine if this is fixed?

Sure!

[tmpsantos]

@jfirebaugh it is not fixed, good news is that I managed to reproduce on the linux app:

map.setStyleURL(style1);
map.setStyleURL(style2);
map.setStyleURL(style3);

view->run();

Sometimes I see style1 instead of style3. I'm working on a fix.

[tmpsantos]

I have a fix already.

[jfirebaugh]

Ah, a request/response race condition -- this is a common error in client-side JS, funny to see it in C++ code. 👍