Asynchronous request returning nil - ios

Question

i've made following Asynchronous request, the problem is that its empty i've tried in the bottom NSLog the fixtures where its empty. I've checked that the nsstring home, away, league and so on returns values and it does. How come the values are not added to the fixtures NSMutableArray
[ProgressHUD show:#"Loading..."];
NSURL *url = [NSURL URLWithString:#"API_URL"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,
NSData *data, NSError *connectionError)
{
jsonResult = [NSJSONSerialization JSONObjectWithData:data
options:0
error:NULL];
int subObjects = ((NSArray *)jsonResult[#"match"]).count;
for (int i = 0; i <= subObjects-1; i++) {
NSString *date = [NSString stringWithFormat:#"%# %#",[[[jsonResult valueForKey:#"match"] valueForKey:#"playdate"] objectAtIndex:i], [[[jsonResult valueForKey:#"match"] valueForKey:#"time"] objectAtIndex:i]];
NSString *identifier = [[NSLocale currentLocale] localeIdentifier];
NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setTimeZone: [NSTimeZone timeZoneWithName:#"US/Arizona"]];
[df setLocale:[NSLocale localeWithLocaleIdentifier:identifier]];
[df setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSDate *myDate = [df dateFromString:[NSString stringWithFormat:#"%#", date]];
NSArray *items = [[NSString stringWithFormat:#"%#", myDate] componentsSeparatedByString:#" "];
NSString *home = [[[jsonResult valueForKey:#"match"] valueForKey:#"hometeam"] objectAtIndex:i];
NSString *away = [[[jsonResult valueForKey:#"match"] valueForKey:#"awayteam"] objectAtIndex:i];
NSString *league = [[[jsonResult valueForKey:#"match"] valueForKey:#"league"] objectAtIndex:i];
[fixtures addObject:
[[NSMutableDictionary alloc] initWithObjectsAndKeys:
items[0], #"date",
items[1], #"time",
home, #"home",
away, #"away",
league, #"league",
nil]];
[sections addObject:
[[NSMutableDictionary alloc] initWithObjectsAndKeys:
items[0], #"date",
nil]];
}
}
];
[self.theTableView reloadData];
[ProgressHUD dismiss];
NSLog(#"%#", fixtures);

Answer 1

The problem is that the request is an asynchronous function
If the function is asynchronous, the function will create another thread and return immediately to execute the next line after the one that invoked the asynchronous function. Meanwhile the new thread will execute some code and, eventually execute the block passed as parameter, and finally the thread is killed and doesn't exist any more.
This means that
NSLog(#"%#", fixtures);
will most likely be executed before the sendAsynchronousRequest has finished it's job, that's why it is returning nil.
Everything you need to do to process the downloaded information should happen inside the completionHandler block, including the call to [self.theTableView reloadData];

Answer 2

It is a non-blocking operation. It means that by calling this method it returns immediatelly while the actual request is performing somewhere in background and then calls the handler block on queue specified in queue parameter.
You should reload tableview from the completion-handler block.
// 1 before request
NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,
NSData *data, NSError *connectionError)
{
// 3 request completed
// some processing
...
[self.theTableView reloadData];
[ProgressHUD dismiss];
}
// 2 immediate return
update
Although you passing the main queue as queue parameter the handler block will be performed on next run loop iteration after you reloading table and logging the values.
// current run loop iteration
NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,
NSData *data, NSError *connectionError)
{
// next run loop iteration
}
// current run loop iteration

Answer 3

if(!fixtures) {
fixtures = [[NSMutableArray alloc] init];
}
[fixtures addObject:#{
#"date": items[0],
#"time": items[1],
#"home": home,
#"away": away,
#"league": league
}];
if(!sections) {
sections = [[NSMutableArray alloc] init];
}
[sections addObject:#{
#"date": items[0]
}];
[self.theTableView reloadData];
[ProgressHUD dismiss];
NSLog(#"%#", fixtures);