Clean Code: How to avoid all those nested if/success blocks? - objective-c

Question

i was wondering how to avoid all those nested if/success blocks? So I am happy with any suggestions how to improve/encapsulate this architecture
- (void)findLocation {
// Show loader.png
[self.searchButton setImage:[UIImage imageNamed:#"loader"] forState:UIControlStateNormal];
// Request url
NSString *url = [NSString stringWithFormat:#"http://api.domain.com/someendpoint/"];
// Send http request
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:url parameters:nil
success:^(AFHTTPRequestOperation *operation, id responseObject) {
// If API returned error
if([responseObject objectForKey:#"error"]) {
// Show an error
// Hide loader
[self.searchButton setImage:[UIImage imageNamed:#"some_button"] forState:UIControlStateNormal];
// Skip everything else
return;
}
// If API returned data
// Init location object
Location * location = [[Location alloc] init];
location.name = [responseObject objectForKey:#"name"];
location.image_url = [responseObject objectForKey:#"image_url"];
location.url = [responseObject objectForKey:#"url"];
location.address = [responseObject objectForKey:#"address"];
// Calculate long/lat from address (API does not provide this information
CLGeocoder *geocoder = [[CLGeocoder alloc] init];
[geocoder geocodeAddressString:location.address completionHandler:^(NSArray *placemarks, NSError *error) {
if (error) {
// Show error
} else {
// Save geo-location to location object
CLPlacemark *place = [placemarks lastObject];
location.location = CLLocationCoordinate2DMake(place.location.coordinate.latitude, place.location.coordinate.longitude);
// Present ResultViewController
ResultViewController *controller = [self.storyboard instantiateViewControllerWithIdentifier:#"ResultView"];
controller.location = location;
controller.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentViewController:controller animated:YES completion:nil];
// Initialize region to monitor
CLCircularRegion *region = [[CLCircularRegion alloc] initWithCenter:location.location radius:150.0 identifier:[[NSUUID UUID] UUIDString]];
// Start monitoring new region
[self.locationManager startMonitoringForRegion:region];
// Stop UpdatingLocation
[self.locationManager stopUpdatingLocation];
// Hide loader
[self.searchButton setImage:[UIImage imageNamed:#"some_button"] forState:UIControlStateNormal];
}];
}
}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
// Show error
// Hide loader
[self.searchButton setImage:[UIImage imageNamed:#"some_button"] forState:UIControlStateNormal];
}
];
}

Answer 1

After your Show error part, return from the function. That way you can put the rest of the code outside the else clause.

Answer 2

As S. McConnel suggests, use first if to handle successful scenario - this makes code reading easier.
Than, as zmbq suggests, wrap it into a function.
Blocks in obj c are not really in "top 10" for their's beauty, just get used with them:)
Some tips for Objective C code style from Google :
http://google-styleguide.googlecode.com/svn/trunk/objcguide.xml#Blocks
As a variant for your Function:
- (void)findLocation {
// Show loader.png
[self.searchButton setImage:[UIImage imageNamed:#"loader"] forState:UIControlStateNormal];
// Request url
NSString *url = [NSString stringWithFormat:#"http://api.domain.com/someendpoint/"];
// Send http request
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:url parameters:nil
success:^(AFHTTPRequestOperation *operation, id responseObject) {
// If API returned data
if([[responseObject objectForKey:#"ErrorCode"] intValue] == 0) {
[self setupLocation:responseObject];
// If API returned error
}
else { // Show an error
// Hide loader
[self.searchButton setImage:[UIImage imageNamed:#"surpriseme_button"] forState:UIControlStateNormal];
}
}];
}
}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
// Hide loader
[self.searchButton setImage:[UIImage imageNamed:#"surpriseme_button"] forState:UIControlStateNormal];
}
];
}