Dropbox upload stops when you leave uiviewcontrolelr - ios

Question

i am facing issue in dropbox upload.
When i am staying on the view on which i have written dropbox upload code then it works fine. But if in between upload process i leave the view and open another screen then upload stops or canceled.
I am using below code
- (void)didPressLink {
self.restClient = [[DBRestClient alloc] initWithSession:[DBSession sharedSession]];
self.restClient.delegate = self;
if(![[DBSession sharedSession] isLinked]) {
[[DBSession sharedSession] linkFromController:self];
}
}
-(void)saveFileOnDropBox{
[self didPressLink];
NSString *filename = [soundOneNew lastPathComponent];
NSString *destDir = #"/";
[[self restClient] uploadFile:filename toPath:destDir withParentRev:nil fromPath:soundOneNew];
}
-(void)restClient:(DBRestClient*)client uploadedFile:(NSString*)destPath
from:(NSString*)srcPath metadata:(DBMetadata*)metadata {
NSLog(#"File uploaded successfully to path: %# %#", metadata.path, destPath);
[[self restClient] loadSharableLinkForFile: [NSString stringWithFormat:#"/%#",metadata.path]];
}
- (void)restClient:(DBRestClient*)client uploadFileFailedWithError:(NSError*)error {
NSLog(#"File upload failed with error - %#", error);
}
- (void)restClient:(DBRestClient*)restClient loadedSharableLink:(NSString*)link
forFile:(NSString*)path
{
NSLog(#"Sharable link %#",link);
NSLog(#"File Path %# ",path);
}
-(void) restClient:(DBRestClient *)client uploadProgress:(CGFloat)progress forFile:(NSString *)destPath from:(NSString *)srcPath {
static NSDate* date = nil;
static double oldUploadedFileSize = 0;
if (!date) {
date = [NSDate date] ;
} else {
NSTimeInterval sec = -[date timeIntervalSinceNow];
date = [NSDate date] ;
NSDictionary *fileAttributes = [[NSFileManager defaultManager] attributesOfItemAtPath:srcPath error:nil];
double uploadedFileSize = (double)[fileAttributes fileSize] * progress;
if (sec) {
NSLog(#"speed approx. %.2f KB/s", (uploadedFileSize - oldUploadedFileSize )/1024.0 / sec );
}
oldUploadedFileSize = uploadedFileSize;
self.uploadAudioProgress.progress = progress;
}
}
How to keep upload process continue even if i leave the view

Answer 1

You call
self.restClient = [[DBRestClient alloc] initWithSession:[DBSession sharedSession]];
to create a new REST client and then
[[self restClient] uploadFile:filename toPath:destDir withParentRev:nil fromPath:soundOneNew];
to do the upload. So, this client is owned by the view controller and is destroyed when the view controller is destroyed - i.e. when you navigate away from it.
You want some other class and an instance of it (probably a singleton or an instance owned by the app delegate and passed to instances that need it) which owns all of the REST clients created and retains them until they are complete.