how to call API from API using NSURLSession block - ios

Question

I have
NSString* FBAuthoValue= #"TESTINGCONSTANT";
On click of Load Button ,it call HitLoadAPI
I am calling my API like below HitLoadAPI, now if at my server end my FBAuthoValue is change i need to Hit another API to get refresh value of FBAuthoValue, and set in HitLoadAPI.
1) User hit HitLoadAPI with FBAuthoValue= #"TESTINGCONSTANT" value, but as in server now FBAuthoValue= #"NewTestCode", so it return httpresponsecode 909,on 909 i need to call refreshFBAuthValue api, and put this value back to HitLoadAPI, and the api work correctly.
2) if FBAuthoValue token change in server, need to call refreshFBAuthValue API, and its return value need to set and call the HitLoadAPI again,without knowing the user.
NOTE: i have to hit multiple API one after another, suppose API-1,API-2,API-3 and so on, and if FBAuthoValue, if in any api ,changes in server then need to refresh that FBAuthoValue and then the same API need to be call, without effecting or blocking to user.
I will reward 50 bounty for sure.
Overview: API-1 call, in the meanwhile if token expire,need to call token expire api, and the API-1 will recall again, without user press Load Button again.
Here is my code
-(void)HitLoadAPI
{
NSError *error;
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
NSURL *url = [NSURL URLWithString:#"[JSON SERVER"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
[request addValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[request addValue:#"application/json" forHTTPHeaderField:#"Accept"];
[request setHTTPMethod:#"POST"];
[request setValue:FBAuthoValue forHTTPHeaderField:FBAUTH];
NSDictionary *mapData = [[NSDictionary alloc] initWithObjectsAndKeys: #"TEST IOS", #"name",
#"IOS TYPE", #"typemap",
nil];
NSData *postData = [NSJSONSerialization dataWithJSONObject:mapData options:0 error:&error];
[request setHTTPBody:postData];
NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSDictionary* headers = [(NSHTTPURLResponse *)response allHeaderFields];
//NSLog(#" headers =%#",headers);
NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
//NSLog(#"response status code: %ld", (long)[httpResponse statusCode]);
if([httpResponse statusCode]==909)
{
FBAuthoValue =[self refreshFBAuthValue];
//what to do here so the current API hit will be call again....
}
}];
[postDataTask resume];
}
-(NSString *) refreshFBAuthValue
{
//hit api to get new refresh token code here need its calling code as well as the block coding cause it response so late which cause return value nil...to HitLoadAPI
return FBaccess_token; //it will return refresh FBaccess_token code
}

Answer 1

You can create a method which you can use to call any api from anywhere in the application, This method takes the parameter specific to an api call, like api url, data which will be included in the body of the request and a completion block which will be called when fbAuthValue is valid.
-(void)HitAPILoadWithFbAuthValue:(NSString*)fbAuthValue apiUrl:(NSString*)apiUrl postData:(NSDictionary*)dict withCompletion:(void (^)(int statusCode,NSURLResponse * apiResponse,NSError * error))completion{
NSError *error;
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
NSURL *url = [NSURL URLWithString:apiUrl];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
[request addValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[request addValue:#"application/json" forHTTPHeaderField:#"Accept"];
[request setHTTPMethod:#"POST"];
[request setValue: fbAuthValue forHTTPHeaderField:FBAUTH];
//post body with dictionary passed as a parameter
NSData *postData = [NSJSONSerialization dataWithJSONObject:dict options:0 error:&error];
[request setHTTPBody:postData];
NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSDictionary* headers = [(NSHTTPURLResponse *)response allHeaderFields];
//NSLog(#" headers =%#",headers);
NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
//NSLog(#"response status code: %ld", (long)[httpResponse statusCode]);
if([httpResponse statusCode]==909)
{
FBAuthoValue =[self refreshFBAuthValue];
//what to do here so the current API hit will be call again....
if (FBAuthoValue){
[self HitAPILoadWithFbAuthValue:fbAuthValue apiUrl:apiUrl postData:dict withCompletion:completion];
}else{
}
}
//if FbAuthValue is valid, call completion block
completion((int)[httpResponse statusCode],response, error);
}];
[postDataTask resume];
}
Usage
I assume you write this method in a separate class called APIManager. So to call this method first create an instance of the APIManager and call like this:
APIManager *sharedManager = [APIManager sharedInstance]
//call API_1
[sharedManager HitAPILoadWithFbAuthValue:FBAuthValue apiUrl:#"API_1_URL" postData:dict_for_first_api withCompletion:^(int statusCode, NSURLResponse *apiResponse, NSError *error) {
if(error != nil){
//handle error here
}else{
//call API_2
[sharedManager HitAPILoadWithFbAuthValue:FBAuthValue apiUrl:#"API_2_URL" postData:dict_for_second_api withCompletion:^(int statusCode, NSURLResponse *apiResponse, NSError *error) {
}];
}
}];