ios - Chaining background NSURLSession uploads -

has been successful in chaining nsurlsession background uploads?

i trying upload huge video file in 5 mb parts using background upload of nsurlsession. uploads has in order. whole thing works fine in foreground. using afnetwoking this, , multi part upload. when app in background, first item uploads fine , starts second 1 in background (in setdidfinisheventsforbackgroundurlsessionblock of afurlsessionmanager). stops abruptly (my best guess in 30 seconds, app woken in background has max lifetime of 30 sec) , nothing happens. expected second session finish in background , call third etc - chain behaviour, not seem work.

i have tried adding file parts single nsurlsession in 1 go httpmaximumconnectionsperhost = 1 - works fine , uploads full file in parts. file parts picked in random order, i.e. part 1 gets uploaded, part 5, part 3, part 10 etc …. tried adding in nsoperationqueue dependency between operations , seems mess entire thing - upload not work @ all.

i know video file can uploaded single file in background, server expects in 5 mb parts. hence guess option chain uploads, or add parts nsurlsession, make sure uploaded in order added.

any appreciated.

my code:

 - (void)viewdidload {      [super viewdidload];     // additional setup after loading view, typically nib.     nsurlsessionconfiguration *config = [nsurlsessionconfiguration backgroundsessionconfigurationwithidentifier:[nsstring stringwithformat:@"%d", rand()]];     afurlsessionmanager *manager = [[afurlsessionmanager alloc] initwithsessionconfiguration:config];     config.httpmaximumconnectionsperhost = 1;     [manager setdidfinisheventsforbackgroundurlsessionblock:^(nsurlsession *session) {          dispatch_async(dispatch_get_main_queue(), ^{             // call completion handler tell system there no other background transfers.             //                completionhandler();             [self upload];         });     }]; }  - (ibaction)start:(id)sender {      [self upload]; }  -(void) upload {      nsstring *filepath = [[nsbundle mainbundle] pathforresource:@"sample" oftype:@"mp4"];     afhttprequestserializer *serializer = [afhttprequestserializer serializer];      nsdictionary *parameters = [nsdictionary dictionarywithobjectsandkeys:@"234", @"u", @"sample.mp4", @"f",nil];     nsmutableurlrequest *request = [serializer multipartformrequestwithmethod:@"post" urlstring:urlstring parameters:parameters constructingbodywithblock:^(id<afmultipartformdata> formdata) {         [formdata appendpartwithfileurl:[nsurl fileurlwithpath:filepath] name:@"data" filename:@"sample.mp4" mimetype:@"video/mp4" error:nil];     } error:nil];       __block nsstring *tempmultipartfile = [nstemporarydirectory() stringbyappendingpathcomponent:@"test"];     tempmultipartfile = [tempmultipartfile stringbyappendingstring:[nsstring stringwithformat:@"%d", rand()]];     nsurl *filepathtemp = [nsurl fileurlwithpath:tempmultipartfile];     __block nsprogress *progress = nil;     [serializer requestwithmultipartformrequest:request writingstreamcontentstofile:filepathtemp completionhandler:^(nserror *error) {         nsurlsessionuploadtask *uploadtask = [manager uploadtaskwithrequest:request fromfile:filepathtemp progress:&progress completionhandler:^(nsurlresponse *response, id responseobject, nserror *error) {              nslog(@"request--> %@.\n response --> %@ \n%@",  request.url.absolutestring ,responseobject, error? [nsstring stringwithformat:@" error: %@", [error localizeddescription]] : @""); //lets know result including failures             [[nsfilemanager defaultmanager] removeitematpath:tempmultipartfile error:nil];          }];         [uploadtask resume];         [manager settaskdidsendbodydatablock:^(nsurlsession *session, nsurlsessiontask *task, int64_t bytessent, int64_t totalbytessent, int64_t totalbytesexpectedtosend) {              nslog(@"uploading");         }];     }]; } 

well, reached out apple clarifications on chaining background uploads - not possible in ios.nsurlsession has resume rate limiter prevents apps executing chained tasks in background explained in https://forums.developer.apple.com/thread/14854. instead, apple suggests batch transfers or other options https://forums.developer.apple.com/thread/14853. other thing asking order multiple tasks in upload queue - i.e, force nsurlsession upload tasks in order in added. pointed dgatwood, using nsoperationqueue not possible , apple mentioned same.as mentioned eskimo in response mail "nsurlsession not guarantee run requests in order , there’s no way enforce that." pretty left option less on original problem.