Multiple downloading progress bar objective c - ios

Question

I am developing a messaging client (as Whatsapp or Line).
I am in troubles because I need to support multiple-downloading files (and uploading), showing a progress bar into each message that have a current downloading process.
The multi-download and upload process is already developed (and works fine), the issue comes when I try to show that progress into the message progress bar.
My "solution" (I don't know if there is a better way to do it) is adding a field "uploaded" and other "downloaded" into the Message entity in CoreData, which save the upload percent or the download percent, and update that field each time that NSURLConnection calls (in upload progress, in download is different):
- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite
but if I try to update the CoreData context inside that method, my user interface freeze.
Ok, that is my problem, I am going to show you the code:
This is my Core Data Message entity:
#property (nonatomic, retain) NSString *ident;
#property (nonatomic, retain) NSString *localId;
#property (nonatomic, retain) NSString *body;
#property (nonatomic, retain) NSString *contentSize;
#property (nonatomic, retain) NSNumber *uploaded;
#property (nonatomic, retain) NSNumber *downloaded;
#property (nonatomic, retain) Avatar *avatar;
#property (nonatomic, retain) Thumbnail *thumbnail;
Here is my class to manage every HTTP connection and here I try to update that entity.
#implementation HTTPConnection
//SOME CODE...
- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite
{
if (self.localId) {
float progress = (float)totalBytesWritten/(float)totalBytesExpectedToWrite;
[self performSelectorOnMainThread:#selector(saveProgressInDatabase:) withObject:[NSNumber numberWithFloat:progress] waitUntilDone:YES];
}
}
- (void)saveProgressInDatabase:(NSNumber *)progress
{
NSManagedObjectContext *context = [[[AppDelegate alloc]init]managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:MESSAGE_ENTITY
inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"localId = %#", self.localId];
[fetchRequest setPredicate:predicate];
NSError *coreError = nil;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&coreError];
Message *currentMessage = [fetchedObjects objectAtIndex:0];
[currentMessage setUploaded:progress];
[context save:&coreError];
[[NSNotificationCenter defaultCenter] postNotificationName:UPLOAD_UPDATED_NOTIFICATION object:self];
}
And here I show the message list and send the messages in a table view:
#implementation TimelineViewController
//SOME CODE...
- (void)viewWillAppear:(BOOL)animated
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(updateTable)
name:UPLOAD_UPDATED_NOTIFICATION
object:nil];
}
- (void)updateTable
{
NSError *error;
[[self fetchedResultsController] performFetch:&error];
if ([[_fetchedResultsController sections]count]>0) {
[table reloadData];
NSIndexPath *scrollIndexPath = [NSIndexPath indexPathForRow:([table numberOfRowsInSection:[[_fetchedResultsController sections]count]-1] - 1) inSection:[[_fetchedResultsController sections]count]-1];
[table scrollToRowAtIndexPath:scrollIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:NO];
}
}
//SOME CODE...
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
Message *info = [_fetchedResultsController objectAtIndexPath:indexPath];
//MORE CODE...
if ([info contentSize]!=NULL) {
[cell.progressBar setHidden:NO];
[cell.progressBar setProgress:[[info uploaded]floatValue]];
}
}
//CODE...
- (IBAction)sendMessageAction:(id)sender
{
CommandServices *services = [[CommandServices alloc]init];
[services sendMessageToGroup:message withMedia:attachedMedia withLocalId:localId];
}
I don't know if that is enough to understand my issue, so I am going to ask two main questions:
Is that a nice way to manage multiple-download with multiple progress bar? I mean, saving the progress into the entity... Or, how could I do it?
Why my app is freeze when I upload or download a file? Maybe I am doing too many access to CoreData?
Thanks so much!

Answer 1

My guess is that you should use the following code to get the NSManagedObjectContext:
AppDelegate *app = (AppDelegate *)[UIApplication sharedApplication].delegate;
NSManagedObjectContext *context = [app managedObjectContext];
instead of:
NSManagedObjectContext *context = [[[AppDelegate alloc]init]managedObjectContext];

Answer 2

Well...after few days thinking about my issue, I realize I was doing too many database access and because of that my app freeze.
I solved it passing to my HTTPConnection object, an instance of the progress bar I want to manage. And I save the progress download/upload only when finishing.
So that is my solution:
In HTTPConnection:
+ (void)setProgressBar:(UIProgressView *)progress
{
[downloadConnection setProgressBar:progress];
}
//CODE...
- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite
{
float progress = (float)totalBytesWritten/(float)totalBytesExpectedToWrite;
if (self.progressBar) {
self.progressBar.progress = progress;
}
if (progress == 1.0) {
[self saveProgressInDatabase:[NSNumber numberWithFloat:progress]];
}
}
And in my message list:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
Message *info = [_fetchedResultsController objectAtIndexPath:indexPath];
//MORE CODE...
if (([info contentSize]!=NULL)&&([[info uploaded]floatValue]<1.0)) {
[HTTPConnection setProgressBar:cell.progressBar];
[cell.progressBar setHidden:NO];
} }
Thanks for your help!