Mapbox background rendering HOW-TO

mapbox-background.m

//First of all you need to modify your Mapbox SDK with the this commit: 
//https://github.com/MrZoidberg/mapbox-ios-sdk/commit/2865d642f163b15f939a906337de4f53bd17a7b6
//Otherwise you will have random crashes during background rendering of maps

//We need semaphore to limit the number of concurrent threads
//Place it one per view
dispatch_semaphore_t _concurrencyLimitingSemaphore = dispatch_semaphore_create(3);

//Also we need cache to store snapshots of the map
NSCache *_imageCache = [NSCache new];

- (RMStaticMapView *)createMapWithInfo:(NSDictionary *)info 
{
	//Create and init RMStaticMapView
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
	UITableViewCell *cell = //create and init cell
	//....

	UIImage *mapImage = [_imageCache objectForKey:@(indexPath.row)];
        if (mapImage) {
            cell.mapImage = mapImage;
        } else {
            //Initially set cell.mapImage.backgroundColor to [UIColor colorWithPatternImage:[RMMapView resourceImageNamed:@"LoadingTile6.png"]]
            cell.mapImage = nil;

            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
                dispatch_semaphore_wait(_concurrencyLimitingSemaphore, DISPATCH_TIME_FOREVER);

                RMStaticMapView *mapView = [self createMapWithInfo:rowInfo];
                UIImage *mapImage = [mapView takeSnapshot];
                if (mapImage)
                {
                    [_imageCache setObject:@(indexPath.row) forKey:parkingId];
                    dispatch_async(dispatch_get_main_queue(), ^(void) {                       
                        [self.tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationNone];
                    });
                }
                dispatch_semaphore_signal(_concurrencyLimitingSemaphore);
            });
        }
        
        return cell;
}

Thanks for sharing this! Have you tried this code with a recent version of Mapbox? I can't get my static maps to render without adding them to the view tree - and adding them as hidden or with alpha == 0, they will just render a black image. Did you add them to the view hierarchy in createMapWithInfo?
(This is with an RMMBTilesSource, not the default tiles from Mapbox)