Slow iOS application

Question

I'd like to find out the reasons why my application is slow. Here's what my view controller is doing:

(viewDidLoad) Retrieves data from a webservice with AFNetworking.
Parses the response, creates custom objects and saves them in a dictionary.
Reloads tableview data to fill it with the custom objects.

My AFNetworking call:

NSString *url = [Utils urlForObjectType:objectGames];

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
AFJSONRequestSerializer *requestSerializer = [AFJSONRequestSerializer serializer];
[requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Accept"];
manager.requestSerializer = requestSerializer;
[manager GET:url parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
    [self didReceiveGames:operation.responseData];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

TableView Methods:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *identifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
    if (cell == nil)
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault  reuseIdentifier:identifier];


        NSString *competition = [competitionNames objectAtIndex:indexPath.section];
        NSArray *competitionGames = [competitions objectForKey:competition];
        Game *game = [competitionGames objectAtIndex:indexPath.row];

        Team *teamA = [game teamA];
        Team *teamB = [game teamB];

        UILabel *labelTeamA = (UILabel *)[cell viewWithTag:100];
        UILabel *labelTeamB = (UILabel *)[cell viewWithTag:101];
        UILabel *labelResultA = (UILabel *)[cell viewWithTag:102];
        [labelResultA setText:nil];
        UILabel *labelResultB = (UILabel *)[cell viewWithTag:103];
        [labelResultB setText:nil];
        UIImageView *imageTeamA = (UIImageView *)[cell viewWithTag:104];
        UIImageView *imageTeamB = (UIImageView *)[cell viewWithTag:105];

        UILabel *labelState = (UILabel *)[cell viewWithTag:106];
        [labelState setText:nil];

        GameState state = [game state];

        NSString *urlImageA = [Utils urlForObjectType:objectTeamImage andID:[teamA teamID]];
        NSString *urlImageB = [Utils urlForObjectType:objectTeamImage andID:[teamB teamID]];

        /* Time Background */
        UIImageView *timeBackground = (UIImageView *) [cell viewWithTag:107];
        [timeBackground setHidden:NO];

        [cell setBackgroundColor:[UIColor clearColor]];

            switch (state) {
                case statePlayed: {
                    [labelResultA setText:[NSString stringWithFormat:@"%d", [game finalResultA]]];
                    [labelResultB setText:[NSString stringWithFormat:@"%d", [game finalResultB]]];
                    [timeBackground setHidden:YES];
                }

                    break;
                case stateFixture: {
                    /* Set labelState to hours */
                    NSDate *date = [game date];
                    NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear | NSCalendarUnitHour | NSCalendarUnitMinute fromDate:date];

                    NSString *minutes;
                    if ([components minute] == 0) {
                        minutes = @"00";
                    } else {
                        minutes = [NSString stringWithFormat:@"%d", [components minute]];
                    }
                    [labelState setText:[NSString stringWithFormat:@"%dh%@", [components hour], minutes]];
                }
                    break;
                case stateCancelled:
                    [labelState setText:@"CANCELLED"];
                    break;
                case statePlaying: {
                    [labelResultA setText:[NSString stringWithFormat:@"%d", [game finalResultA]]];
                    [labelResultB setText:[NSString stringWithFormat:@"%d", [game finalResultB]]];
                    [timeBackground setHidden:YES];
                }
                    break;
                case statePostponed:
                    [labelState setText:@"POSTPONED"];
                    break;
                case stateSuspended:
                    [labelState setText:@"SUSPENSED"];
                    break;
                default:
                    break;
            }

            [labelTeamA setText:[teamA name]];
            [labelTeamB setText:[teamB name]];
            [imageTeamA setImageWithURL:[NSURL URLWithString:urlImageA]];
            [imageTeamB setImageWithURL:[NSURL URLWithString:urlImageB]];

    return cell;

}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    NSArray *competitionGames = [competitions objectForKey:[competitionNames objectAtIndex:section]];
    return [competitionGames count];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return [competitionNames count];
}

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
    UIView *header = [[NSBundle mainBundle] loadNibNamed:@"GamesHeaderIPAD" owner:self options:nil][0];

    NSString *competitionName = [[competitionNames objectAtIndex:section] uppercaseString];

    UILabel *labelCompetition = (UILabel *)[header viewWithTag:100];
    [labelCompetition setText:competitionName];

    return header;
}

-(CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
    return 42;
}

EDIT: It has nothing to do with AFNetworking, I just saved the response in NSUserDefaults, read it from there and it is still slow.

Thanks

"Retrieves data from a webservice with AFNetworking" on main thread? — Nikita Took, Mar 04 '14 at 11:06
What do you mean "slow"? Do you have problems in viewDidLoad function? or your UI opens immediatelly, but data comes later? — Nikita Took, Mar 04 '14 at 11:18
UI opens immediatelly, data comes later and by slow I mean the tableview is laggy while scrolling. — diogo.appDev, Mar 04 '14 at 11:21
Could you update your question to have the code for all your tableview methods in the view controller? — Adam Knights, Mar 04 '14 at 11:28
What is setImageWithUrl? It's not a native method for UIImageView — Nikita Took, Mar 04 '14 at 11:39
Just a thought - as the user scrolls through the uitableview is it waiting to download the pictures from the url until the cell is on screen? Do those pictures need to be downloaded asynchronously? If not then you need to profile - although slightly dated this http://www.raywenderlich.com/23037/how-to-use-instruments-in-xcode may be a good starting point — Adam Knights, Mar 05 '14 at 12:11

score 0 · Answer 1 · edited May 23 '17 at 12:10

0

Make the webservice call in another thread.

Personally, I like to use Grand Central dispatch. This question using dispatch_sync in Grand Central Dispatch shows some good syntax. You place everything to run in the background in the dispatch_async part, when the service has got it's data you can update/reload your tableview safely in the dispatch_sync part.

edited May 23 '17 at 12:10

Community

1
1

answered Mar 04 '14 at 11:21

Adam Knights

2,141
1
25
48

score 0 · Answer 2 · edited Mar 04 '14 at 11:33

You can use this method for background processing:

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
    NSString *url = [Utils urlForObjectType:objectGames];

    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    AFJSONRequestSerializer *requestSerializer = [AFJSONRequestSerializer serializer];
    [requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Accept"];
    manager.requestSerializer = requestSerializer;
    [manager GET:url parameters:nil success:^(AFHTTPRequestOperation *operation,id responseObject) {
        dispatch_async(dispatch_get_main_queue(), ^{
           [self didReceiveGames:operation.responseData];
        }];
    }     
    failure:^(AFHTTPRequestOperation *operation, NSError *error) {

         dispatch_async(dispatch_get_main_queue(), ^{
           [self didReceiveGames:operation.responseData];
        }];
    NSLog(@"Error: %@", error);
       }];
    });

score 0 · Answer 3 · answered Mar 04 '14 at 11:47

0

The first step in speeding up in that case is replacing viewWithTag with IBOutlets.

answered Mar 04 '14 at 11:47

Nikita Took

3,980
25
33

Do you think this will have significant improvement in the scrolling speed? – diogo.appDev Mar 04 '14 at 12:00
@diogo.appDev I think you should try to profile to see where the bottleneck is. – Nikita Took Mar 04 '14 at 13:28

Slow iOS application

3 Answers3