Perform a HTTP POST request and then a HTTP GET request - ios

Question

I am a beginner in handling connections in iOS. I want to perform a POST request and a GET request to a url. The thing is that I need to first do the POST so I can get an access token parsed in a JSON that later will place in the header of the GET request, so I can retrieve the login data I need. I am using custom delegate methods, but when I run this, the GET request is performed earlier than the POST, so I cannot get the key before the GET is done. Is there any way to perform the POST first and then the GET? Here is my code:
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
//params
self.user = #"carlos";
self.pass = #"1234";
self.grantType = #"password";
self.clientId = #"7da713e69afc96cf894e";
self.clientSecret = #"2c14ec54cfdfd6faec4ef56ca7f0870ab83f820b";
// Set the side bar button action. When it's tapped, it'll show up the sidebar.
self.sideBarButton.target = self.revealViewController;
self.sideBarButton.action = #selector(revealToggle:);
// Set the gesture
[self.view addGestureRecognizer:self.revealViewController.panGestureRecognizer];
[self httpPostWithCustomDelegate];
[self sendHTTPGet];
}
-(void) httpPostWithCustomDelegate
{
NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration: defaultConfigObject delegate: nil delegateQueue: [NSOperationQueue mainQueue]];
NSURL * url = [NSURL URLWithString:#"http://192.237.241.175:8090/oauth2/access_token/"];
NSMutableURLRequest * urlRequest = [NSMutableURLRequest requestWithURL:url];
NSString * params =[NSString stringWithFormat:#"&username=%#&password=%#&grant_type=%#&client_id=%#&client_secret=%#&scope=write",self.user,self.pass,self.grantType,self.clientId,self.clientSecret];
[urlRequest setHTTPMethod:#"POST"];
[urlRequest setHTTPBody:[params dataUsingEncoding:NSUTF8StringEncoding]];
NSURLSessionDataTask * dataTask =[defaultSession dataTaskWithRequest:urlRequest
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSLog(#"Retrieving Data");
// NSLog(#"Response:%# %#\n", response, error);
if(error == nil)
{
//Test Display
// NSString * text = [[NSString alloc] initWithData: data encoding: NSUTF8StringEncoding];
// NSLog(#"Data = %#",text);
self.responseDataPost = [[NSMutableData alloc] init];
[self.responseDataPost appendData:data];
NSError *error;
NSMutableDictionary *receivedData = [NSJSONSerialization JSONObjectWithData:self.responseDataPost options:NSJSONReadingMutableContainers error:&error];
//obtener del dictionary el access token y meter como header Authorization Bearer + id
//NSArray *accessToken = [receivedData valueForKeyPath:#"access_token"];
self.connTxtPost.text = [receivedData valueForKeyPath:#"access_token"];
self.recData = [receivedData valueForKeyPath:#"access_token"];
}
}];
[dataTask resume];
}
-(void) sendHTTPGet
{
NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration: defaultConfigObject delegate: self delegateQueue: [NSOperationQueue mainQueue]];
NSURL * url = [NSURL URLWithString:#"http://192.237.241.175:8090/snippets/"];
NSMutableURLRequest * urlRequest = [NSMutableURLRequest requestWithURL:url];
[urlRequest setHTTPMethod:#"GET"];
self.connTxtGet.text = self.recData ;
[urlRequest setValue:self.recData forHTTPHeaderField:#"Authorization"];
NSURLSessionDataTask * dataTask =[defaultSession dataTaskWithRequest:urlRequest
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
//NSLog(#"Response:%# %#\n", response, error);
if(error == nil)
{
NSString * text = [[NSString alloc] initWithData: data encoding: NSUTF8StringEncoding];
NSLog(#"Data = %#",text);
}
}];
[dataTask resume];
}

Answer 1

You don't need to call these two method all together.
[self httpPostWithCustomDelegate];
[self sendHTTPGet];
You are making two request at the same time. But which response will come first you can not determine it. As you need data from "POST" request to make the "GET" request. Do something like this:
-(void) httpPostWithCustomDelegate{
.............
NSURLSessionDataTask * dataTask =[defaultSession dataTaskWithRequest:urlRequest
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
...................
...................
self.connTxtPost.text = [receivedData valueForKeyPath:#"access_token"];
self.recData = [receivedData valueForKeyPath:#"access_token"];
[self sendHTTPGet];
}
}];
[dataTask resume];
}
This will make sure when you make the "GET" request you have the "access_token". Hope this will work just fine. :)