Collecting results into NSArray from a block that is in a while loop

Question

I'm trying to run a block in a loop and collect the results in a NSMutableArray. The issue I'm having is that since it's asynchronous, I'm having trouble finding out when all of the blocks have finished executing. I'm trying to compare the [array count] with the number of block calls made. My thought is that this would only trigger once but I'm finding that 'I MADE IT!' will never be logged or that it will be logged multiple times. I also feel like that's a hacky solution but I can't think of a better way.

Sorry for the long code chunk but I put in all of the code needed so if somebody wanted to, they could copy & paste and see the results that I'm getting. The actual meat and potatoes of my question starts at the while loop about 2/3 of the way down.

It's probably obvious that I'm new to iOS development so any other constructive critisisms are welcome.

NSDate *now = [NSDate date];

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

NSDateComponents *zeroOutAfterHourComponents = [gregorian components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit fromDate:[NSDate date]];
NSDate *gregorianNow = [gregorian dateFromComponents:zeroOutAfterHourComponents];

NSDateComponents *componentsToSubtract = [[NSDateComponents alloc] init];
[componentsToSubtract setDay:-7];
//[componentsToSubtract setHour:-24];

NSDate *startingDate = [gregorian dateByAddingComponents:componentsToSubtract toDate:gregorianNow options:0];

NSDateComponents *addAnHourComponent = [[NSDateComponents alloc] init];
[addAnHourComponent setHour:1];
NSDate *startingDatePlusAnHour = [gregorian dateByAddingComponents:addAnHourComponent toDate:startingDate options:0];

CMStepCounter *stepCounter = [CMStepCounter new];
NSOperationQueue *stepQueue = [NSOperationQueue new];
stepQueue.name = @"Step Counter Queue";

__block NSMutableArray *dateKeyAndSccSteps = [NSMutableArray new];

NSTimeInterval time = [now timeIntervalSinceDate:startingDate];
int hours = time / 60 / 60;

// + 1 is added to take account of the current hour
int totalDictionaryCount = hours + 1;

NSLog(@"totalDictionaryCount: %d", hours);
NSLog(@"StartingDate: %@", startingDate);
NSLog(@"StartingDatePlusAnHour: %@", startingDatePlusAnHour);
NSLog(@"Now: %@", now);

while ([startingDate compare:now] == NSOrderedAscending) {
    [stepCounter queryStepCountStartingFrom:startingDate to:startingDatePlusAnHour toQueue:stepQueue withHandler:^(NSInteger numberOfSteps, NSError *error) {

        NSDateFormatter *formatterForDate = [[NSDateFormatter alloc] init];
        [formatterForDate setDateFormat:@"yyyy-MM-dd"];
        NSString *dateKey =[NSString stringWithFormat:@"%@", [formatterForDate stringFromDate: startingDate]];

        [dateKeyAndSccSteps addObject:@[dateKey, @"TestValue"]];

        NSLog(@"array count: %lu - totalDictionaryCount: %d", (unsigned long)[dateKeyAndSccSteps count], totalDictionaryCount);
        if ([dateKeyAndSccSteps count] == totalDictionaryCount){
            NSLog(@"I MADE IT!");
        }
    }];

    startingDate = startingDatePlusAnHour;
    startingDatePlusAnHour = [gregorian dateByAddingComponents:addAnHourComponent toDate:startingDatePlusAnHour options:0];
};
NSLog(@"Finished While Loop: %@", now);

UPDATE - 2013-12-13

I updated my while loop with dispatch groups. I also changed the stepCounter block to use [NSOperationQueue mainQueue].

It works but I'm not sure if I'm using them correctly.

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_group_t group = dispatch_group_create();

while ([startingDate compare:now] == NSOrderedAscending) {

    dispatch_group_async(group, queue, ^{

        [stepCounter queryStepCountStartingFrom:startingDate to:startingDatePlusAnHour toQueue:[NSOperationQueue mainQueue] withHandler:^(NSInteger numberOfSteps, NSError *error) {

            << same existing code as original >>

        }];

    });

    startingDate = startingDatePlusAnHour;
    startingDatePlusAnHour = [gregorian dateByAddingComponents:addAnHourComponent toDate:startingDatePlusAnHour options:0];
};