Refactoring my code for asynchronous NSURLConnection - iphone

Question

There are problems with using synchronous requests. The problem is that I am not really sure how to refactor the code below to use an asynchronous request to accomplish the following two tasks:
Use a UIActivityIndicatorView subview to notify of active fetching;
Implement a Reachability check before the connection request to ensure that there is an Internet connection and that the host is available, i.e. reachabilityWithHostName:#"wwww.mywebhostingisterrible.com".
Currently I have a Fetcher class with a +(Fetcher *)sharedFetcher singleton that is used in all of my view controllers to fetch data. Currently all data is fetched using the following code:
- (NSString *)stringWithUrl:(NSURL *)url {
NSMutableURLRequest *urlRequest = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:30];
NSData *urlData;
NSURLResponse *response;
NSError *error;
urlData = [NSURLConnection sendSynchronousRequest:urlRequest
returningResponse:&response
error:&error];
return [[NSString alloc] initWithData:urlData encoding:NSUTF8StringEncoding];
}
A method that fetches looks like this:
-(NSArray *)fetchDogFoodListing {
NSString *urlString = [NSString stringWithFormat:#"%#query/dogFood/%#/%lli/%#/%#",self.connectionUrl,self.queryCriteria.dogFoodName,self.queryCriteria.dogFoodBrandId,self.queryCriteria.dogFoodIngredients,self.queryCriteria.dogFoodBrand];
NSString *json = [self stringWithUrl:[NSURL URLWithString:urlString]];
return [self.factory buildIKDogFoodArrayWithJSON:json];
}
and a call from the UIViewController in -(void)viewDidLoad looks like this:
self.dogFoods = [[IKFetcher sharedFetcher] fetchDogFoodListing];
I have thought about implementing a delegate in this situation but I am very shaky on how delegation ought to work. I'm not even sure which way it should go. Should the Fetcher have a FetcherDelegate that can notify the view controller of when it is done, so the UI can update? Should the view controller have a delegate so that the fetcher can update the view when stuff is done?
I'm sure based on my questions you can see my inexperience with delegation, so I would appreciate any help.

Answer 1

You could do something like this
dispatch_async(queue, ^{
NSMutableURLRequest *urlRequest = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:30];
NSData *urlData;
NSURLResponse *response;
NSError *error;
urlData = [NSURLConnection sendSynchronousRequest:urlRequest
returningResponse:&response
error:&error];
dispatch_async(dispatch_get_main_queue(), ^{
//.. do stuff with data here...
}
}
or you could just do the sendSynchronousRequest code inside a dispatch_sync if you want the connection to be synchronous, though you should really should be as asynchronous as possible.

Answer 2

you may want to look at the brilliant framework by Mugunth Kumar:
http://blog.mugunthkumar.com/products/ios-framework-introducing-mknetworkkit
I plan on using this for NSURLConnection in my future projects