Why is my first reponse null? - ios

Question

I have a Location.m model, which I use to obtain latitude and longitude. When I have those, I call my delegate method which is implemented in my Foursquare.m model.
Location.h looks like this:
#class Location;
#protocol LocationDelegate <NSObject>
- (void)location:(Location *)loc didFinishFindingLocation:(CLLocation *)location;
#end
#interface Location : NSObject <CLLocationManagerDelegate>
#property (nonatomic, weak) id <LocationDelegate> delegate;
- (void)startLocationManager;
#end
Location.m:
#implementation Location
{
CLLocationManager *_locationManager;
BOOL _locationIsUpdated;
}
- (void)startLocationManager
{
NSLog(#"In startLocationManager");
_locationManager = [[CLLocationManager alloc] init];
_locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;
_locationManager.delegate = self;
_locationIsUpdated = NO;
[_locationManager startUpdatingLocation];
}
#pragma mark - LocationManager Delegates
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
if (locations && _locationIsUpdated == NO) {
self.location = [locations lastObject];
NSLog(#"%#", _location);
_locationIsUpdated = YES;
[self.delegate location:self didFinishFindingLocation:self.location];
}
}
#end
When the delegate method is called from the Foursquare model, and I NSLog out the response in an array (called self.dataResponse). It always outputs (null) first, then all the JSON. Why does that happen? If I NSLog out dataDictionary (see code below) directly, the JSON output shows a error-code:400 and nothing is printed. Couple of milliseconds after everything is printed and seems to be working fine...
Here is a picture:
When I log the dataDictionary
Here is the delegate method implemented in Foursquare.m:
- (void)location:(Location *)loc didFinishFindingLocation:(CLLocation *)location
{
loc.delegate = self;
self.resultFromResponse = [[NSMutableArray alloc] init];
NSString *search = [NSString stringWithFormat:#"https://api.foursquare.com/v2/venues/search?ll=%f,%f&radius=2000&categoryId=4d4b7105d754a06374d81259&client_id=%#&client_secret=%#&v=%#", location.coordinate.latitude, location.coordinate.longitude, kFourdquareAPIKey, fFoursquareSecret, [Foursquare getCurrentDate]];
NSURL *url = [NSURL URLWithString:search];
NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:config];
NSURLSessionDataTask *task = [session dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSDictionary *dataDictionary = (NSDictionary *)[NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
if (!error) {
self.dataResponse = dataDictionary[#"response"][#"venues"];
NSLog(#"%#", self.dataResponse);
for (NSDictionary *venue in self.dataResponse) {
FSDataFromJSON *data = [[FSDataFromJSON alloc] init];
data.name = venue[#"name"];
data.phone = venue[#"phone"];
data.location = venue[#"location"];
[self.resultFromResponse addObject:data];
}
//[[NSNotificationCenter defaultCenter] postNotificationName:#"JSONRequestFinishedLoading" object:nil];
} else {
NSLog(#"%#", error.description);
}
}];
[task resume];
}
At the very end, these models is started in my MainViewController:
_location = [[Location alloc] init];
[_location startLocationManager];
_foursquare = [[Foursquare alloc] init];
[_foursquare location:_location didFinishFindingLocation:_location.location];

Answer 1

From what I can tell, the last line of code in your question is likely the problem:
[_foursquare location:_location didFinishFindingLocation:_location.location];
You shouldn't be calling your delegate method explicitly (before the location has been set). Instead, you should be waiting for the CLLocation callback to kick it off.
Other thoughts:
If the Location class has a .location property, I think that's confusing.
Location.m is not a model, it's the file containing the class implementation. I'd say the Location class is a model.
You could simplify your delegate method as didFindLocation:(Location *)location since you can get the CLLocation in the method as location.location.
What are the three most important factors in real estate? location.location.location!