[ios] black screen with offline maps

[rsimenok]

iOS
MapBox 3.2.0

Hello, i have problems with downloading offline package.

Firstly I hope i check right if offline pack available, because if i had offline pack i don't need to download it again.

if ([[MGLOfflineStorage sharedOfflineStorage] packs].count == 0) {
    NSLog(@"START OFFLINE PACK DOWNLOAD");
    [[YMapDownloader downloader] startOfflinePackDownload];
}

YMapDownloader is my NSObject, where i put code from official example, here is full code of my class

how i create region

CLLocationCoordinate2D sw = CLLocationCoordinate2DMake(32.147344404778963, -64.89344945400417);
CLLocationCoordinate2D ne = CLLocationCoordinate2DMake(32.471673244603323, -64.643860247099894);

id <MGLOfflineRegion> region = [[MGLTilePyramidOfflineRegion alloc] initWithStyleURL:nil
                                                                              bounds:MGLCoordinateBoundsMake(sw, ne)
                                                                       fromZoomLevel:9.8
                                                                         toZoomLevel:20.0];

so when i call startOfflinePackDownload i start downloading

// Start downloading.
[pack resume];

But i don't get any notification about progress, even no NetworkActivityIndicator in status bar.
After i don't see any activity i try to open map and it was black, i mean black screen, no map. When i commented pack downloading, recompile app and open map i start get warnings:

Unable to make space for entry
2016-04-08 02:11:54.316 MyApp[420:64640] [WARNING]

so as i understand it's connected #4411

Steps to trigger behavior

Use code from example but with this region:

CLLocationCoordinate2D sw = CLLocationCoordinate2DMake(32.147344404778963, -64.89344945400417);
CLLocationCoordinate2D ne = CLLocationCoordinate2DMake(32.471673244603323, -64.643860247099894);

id <MGLOfflineRegion> region = [[MGLTilePyramidOfflineRegion alloc] initWithStyleURL:nil
                                                                              bounds:MGLCoordinateBoundsMake(sw, ne)
                                                                       fromZoomLevel:9.8
                                                                         toZoomLevel:20.0];

Expected behavior

Downloaded offline pack.

Actual behavior

No pack downloaded.

[1ec5]

Where are you checking the number of packs? That array is populated asynchronously and may be nil for an undefined period of time after launch. You should register for KVO change notifications on that key path and only start the download when the change kind is NSChangeKindSetting.

The SDK doesn't handle displaying the network activity indicator – your application can manage that.

/cc @friedbunny

[rsimenok]

Where are you checking the number of packs?

@1ec5 in viewWillAppear of my initial ViewController. He doesn't contains MapBox map.

[1ec5]

I wonder if that's too soon. Can you check whether packs is in fact nil rather than empty? (The code you posted above doesn't distinguish.) If it's nil, you should try KVO to detect when the packs are discovered. See MBXOfflinePacksTableViewController for inspiration.

[rsimenok]

@1ec5 not nil...(

I wonder why after [pack resume]; i doesn't get any notifications.

Well i think i found problem.

[[YMapDownloader downloader] startOfflinePackDownload];

+(YMapDownloader *)downloader {
    return [[YMapDownloader alloc] init];
}

YMapDownloader instance dying very fast, so i didn't get notifications, but as i understand pack was loading.
NOTE: Black screen means that map is loading.
So i take strong ref on YMapDownloader instance and all is working, but i get warnings:
[WARNING] {DefaultFileSource}[Database]: Unable to make space for entry

And the last question, is it possible to check for packs on application start?

[1ec5]

It isn't possible to check synchronously at application launch, unfortunately.

[rsimenok]

@1ec5 Two more question please :)

1. How to get all size of region(all packs)?
2. How to detect if user downloaded all packs for region or no? Or detect if region was downloaded?

[lethianqt94]

I have same questions:

1. How to get all size of region(all packs)?
2. How to detect if user downloaded all packs for region or no? Or detect if region was downloaded?

[1ec5]

1. For each offline pack in MGLOfflineStorage.packs, call -requestProgress. The progress arrives asynchronously, so register for MGLOfflinePackProgressChangedNotification notifications, which come with progress information including the size taken up by the region. You'll need to sum up the sizes yourself.
2. Call -requestProgress on the pack, as above.

See the offline storage documentation for more information about notifications and progress.