Objective C Loading Icon on Timer

Question

I have created a loading icon for my application. While the application is loading the map and placing the markers I have a loading icon displaying on the screen rotating. With my current code the loading icon shows, but only rotates when the markers are all placed on the map and everything is finished loading. I have tried about everything, can anyone help?

I will attach code below, I do understand this is not the best way to do it and I plan to neaten it up once I find out what I am doing wrong getting it to rotate when the map is loading.

Thanks.

- (void)viewDidLoad
{
    [super viewDidLoad];
    loading=@"0";

    rotateTimer = [NSTimer scheduledTimerWithTimeInterval:0.3
                                                   target:self
                                                 selector:@selector(rotateMove)
                                                 userInfo:nil
                                                  repeats:YES];
}

-(void)rotateMove
{
    if([loading  isEqual:@"1"])
    {
        [rotateTimer invalidate];
        rotateTimer = nil;
    }
    if([loading  isEqual:@"0"])
    {
        NSLog(@"move");
        [UIView animateWithDuration:1.0f delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
            [self.rotate setTransform:CGAffineTransformRotate(self.rotate.transform, M_PI_2)];
        } completion:^(BOOL finished){
            if (finished) {
            }
        }];
    }
}

EDITED: ADDED MAP CODE BELOW

-(void)mapload
{

 [self.mapView clear];


NSString *lat = [[NSString alloc] initWithFormat:@"%g", latitude];
NSString *lng = [[NSString alloc] initWithFormat:@"%g", longitude];
NSURL *blogURL = 
NSLog(@"URL = %@", blogURL);
NSData *jsonData = [NSData dataWithContentsOfURL:blogURL];
if(jsonData == nil)
{
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Connection Error" message:@"Please check your internet connection and try again." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
    return;
}
else{



    NSError *error = nil;
    NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error];
    NSArray *test = [dataDictionary objectForKey:@"test"];

    self.bottombutton.hidden=FALSE;
    self.time.hidden=FALSE;
    self.mins.hidden=FALSE;
   self.rotate.hidden=TRUE;
    int tes = [[test[0] valueForKey:@"time"] intValue];


    }

    for (int i = 0; i < [test count]; i++)    {
        for(NSDictionary *coordinates in test){

            double la=[coordinates[@"lat"] doubleValue];
            double lo=[coordinates[@"long"] doubleValue];

            CLLocation * loca=[[CLLocation alloc]initWithLatitude:la longitude:lo];
            CLLocationCoordinate2D coordi=loca.coordinate;

            GMSMarker *marker= [[GMSMarker alloc] init];
            marker=[GMSMarker markerWithPosition:coordi];
            marker.snippet = coordinates[@"name"];
            marker.map = self.mapView;
            marker.appearAnimation = kGMSMarkerAnimationPop;

            UIImage * image = [UIImage imageNamed:@"mapiconlarge"];
            CGSize sacleSize = CGSizeMake(45, 45);
            UIGraphicsBeginImageContextWithOptions(sacleSize, NO, 0.0);
            [image drawInRect:CGRectMake(0, 0, sacleSize.width, sacleSize.height)];
            UIImage * resizedImage = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();

            NSLog(@"markeradded");
            marker.icon = resizedImage;
            NSLog(loading);


        }
      }


}



 }

Answer 1

We need to tease apart the part of your code that should be done in the background -- at the very least, the network request -- and the code that must be done on the main -- anything that changes the UI...

// here, everything you do to prepare for the network request

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    // make the network request
    NSData *jsonData = [NSData dataWithContentsOfURL:blogURL];
    dispatch_async(dispatch_get_main_queue(), ^{
        // here everything you do after with the json data result
    });
});

So you don't drive yourself crazy with syntax, build two methods, the first one produces blogURL for use on the network request, the second, takes the NSData result and does everything else. This way, there's just a one-liner method invocation nested in that inner dispatch.