How do I use a variable outside of a GET request? - ios

Question

I would like to:
Initialise a variable prior to an GET request (AFNetworking)
Assign to the variable inside the request success
Use the variable once request is done
The error I get:
When trying to do something the variable after the GET request, it breaks, claiming there is no value to the variable yet
The following is my code, how do I solve this problem?
- (IBAction)synchronisePressed {
//Would like to initialise a variable here
__block NSArray *received;
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:#"http://foo.com/foo/"
parameters:nil
success:^(AFHTTPRequestOperation *operation, id responseObject) {
//Assign responseObject to received object
received = responseObject;
NSLog(#"Woo: %#", #"got here");
}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Error: %#", error);
}];
//Now outside of request, so use array in some way
[foo received];
}

Answer 1

The problem is not in the code or in the request. The problem is the GET method of AFNetworking is asynchronous and you are trying to use it synchronously.
This means that the GET method will start working and sit in the background working away and the rest of your code will continue as normal. Only when the GET request has finished will the code inside the blocks get run.
This code be 1 second or 30 seconds or any amount of time after you start the request.
Put in an NSLog before your line [foo received];.
The order of logs will be like so...
1. Created NSArray called received.
2. Pass NSArray called received to method foo.
// some time later
3. AFNetworking GET request finished.
4. Assign value from the GET request to the NSArray called received.
What you need to do in this case is put your call to [foo received]; INSIDE the completion block.
Something like this...
- (IBAction)synchronisePressed
{
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:#"http://foo.com/foo/"
parameters:nil
success:^(AFHTTPRequestOperation *operation, id responseObject) {
//Assign responseObject to received object
NSArray *received = responseObject;
NSLog(#"Woo: %#", #"got here");
[foo received];
}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Error: %#", error);
}];
}
Now you will get...
1. Created NSArray called received.
// some time later
2. AFNetworking GET request finished.
3. Assign value from the GET request to the NSArray called received.
4. Pass NSArray called received to method foo.