Calling two NSURLSessionTask completion blocks one after another? - ios

Question

I have the following setup that uses AFNetworking to make calls to my server. I have used an example I found on the internet to include a completion block so I know when the call has finished.
File "FCEngine.m"
- (void)fetchBusinessProfile:(NSString *)userID userAccessToken:(NSString *)userAccessToken completion:(void (^)(NSDictionary *json, BOOL success))completion {
/// Validate the user token again the user id.
NSDictionary *parameters = [[NSDictionary alloc]initWithObjectsAndKeys:userAccessToken,#"user_access_token",
userID,#"user_id",
nil];
AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
AFHTTPRequestSerializer *serializer = [AFHTTPRequestSerializer serializer];
manager.requestSerializer = serializer;
manager.responseSerializer = [AFJSONResponseSerializer serializerWithReadingOptions:NSJSONReadingAllowFragments];
[manager POST:#"" parameters:parameters progress:nil success:^(NSURLSessionTask *task, id responseObject) {
NSLog(#"JSON Business Profile: %#", responseObject);
fetchBusinessProfileCompletion(responseObject, YES);
} failure:^(NSURLSessionTask *operation, NSError *error) {
//NSLog(#"Error: %#", error);
NSMutableDictionary *errorResponse = [[NSMutableDictionary alloc] init];
[errorResponse setObject:#"connection_error" forKey:#"state"];
[errorResponse setObject:[error localizedDescription] forKey:#"description"];
fetchBusinessProfileCompletion(errorResponse, YES);
}];
}
- (void)fetchNotifications:(NSString *)userID userAccessToken:(NSString *)userAccessToken completion:(void (^)(NSDictionary *json, BOOL success))completion {
/// Validate the user token again the user id.
NSDictionary *parameters = [[NSDictionary alloc]initWithObjectsAndKeys:userAccessToken,#"user_access_token",
userID,#"user_id",
nil];
AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
AFHTTPRequestSerializer *serializer = [AFHTTPRequestSerializer serializer];
manager.requestSerializer = serializer;
manager.responseSerializer = [AFJSONResponseSerializer serializerWithReadingOptions:NSJSONReadingAllowFragments];
[manager POST:#"" parameters:parameters progress:nil success:^(NSURLSessionTask *task, id responseObject) {
//NSLog(#"JSON: %#", responseObject);
completion(responseObject, YES);
} failure:^(NSURLSessionTask *operation, NSError *error) {
//NSLog(#"Error: %#", error);
NSMutableDictionary *errorResponse = [[NSMutableDictionary alloc] init];
[errorResponse setObject:#"connection_error" forKey:#"state"];
[errorResponse setObject:[error localizedDescription] forKey:#"description"];
completion(errorResponse, YES);
}];
}
The following is how I make the call on Main View Controller
- (void)MyMethods {
[self.fcEngine fetchBusinessProfile:userID userAccessToken:userAccessToken completion:^(NSDictionary *json, BOOL success) {
/// Response here
}];
[self.fcEngine fetchNotifications:self.userID userAccessToken:self.userAccessToken completion:^(NSDictionary *json, BOOL success) {
//// Response here
}];
}
Now the problem is that the 2 calls are made one after another and when I fetch the data for one e.g. "fetchBusinessProfile" the competition block on both is called.
Have I set this up wrong? If 2 or more calls I only want the completion to be called for that particular block and not them all.

Answer 1

I don't think you understand asynchronous as well as completion blocks. If you make the 2 network calls as defined above, they can happen in any order. The completion in fetchBusinessProfile and fetchNotifications will be different completion blocks ... unless you make them the same.
For example:
[self.fcEngine fetchBusinessProfile:userID userAccessToken:userAccessToken completion:^(NSDictionary *json, BOOL success) {
/// Handle response
// Note calling the SAME completion block
sameCompletionBlockAlreadyDefined();
}];
[self.fcEngine fetchNotifications:self.userID userAccessToken:self.userAccessToken completion:^(NSDictionary *json, BOOL success) {
//// Handle response
// Note calling the SAME completion block
sameCompletionBlockAlreadyDefined();
}];
In this case, sameCompletionBlockAlreadyDefined() is some already defined block. In this case, the body of the block of each call is indeed, but funnel to the same call via sameCompletionBlockAlreadyDefined. It is possible you are confused because completion happens to be named the same in your first snippet.
Note your question is really poorly phrased so it isn't fully clear on what you mean.
The larger question is what is your goal? Do you want only one completion block to be called at the end? Or you want fully distinct completion blocks? Both require different techniques. Be clear on what your goal is.
The former would be best service with a dispatch_group. The latter requires different completion blocks.
An example of dispatch group would be something like:
dispatch_group_t group = dispatch_group_create();
dispatch_group_enter(group);
[self.fcEngine fetchBusinessProfile:userID userAccessToken:userAccessToken completion:^(NSDictionary *json, BOOL success) {
/// Handle response
dispatch_group_leave(group);
];
self.fcEngine fetchNotifications:self.userID userAccessToken:self.userAccessToken completion:^(NSDictionary *json, BOOL success) {
//// Handle response
dispatch_group_leave(group);
}];
dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
// This would be some completion block which means all is done
completion();