Bit.ly API Objective C retrieve access_token - objective-c

Question

I have a quick question.
I want the user to enter his username (email) and password and I want to get an access token from the bit.ly api.
I tried so far:
NSString *authStr = [NSString stringWithFormat:#"%#:%#", #"username", #"password"];
NSData *authData = [authStr dataUsingEncoding:NSUTF8StringEncoding];
NSString *authValue = [NSString stringWithFormat:#"Basic %#", [authData base64Encoding]];
[request setValue:authValue forHTTPHeaderField:#"Authorization"];
However this does not work.
What I need is to get this command of curl to run in objective c:
curl -u "username:password" -X POST "https://api-ssl.bitly.com/oauth/access_token"
I know I can set the method to POST but I am not sure how to set username:password :|
I also tried using
curl -u "CLIENT_ID:CLIENT_SECRET" -d "grant_type=password" -d "username=USERNAME" \
-d "password=PASSWORD" https://api-ssl.bitly.com/oauth/access_token
however I still do not know how ti set the input of client id and client secret.
Any help on how I can set those information into the request would help me much!
Jack

Answer 1

Admittedly, things like AFNetworking do make working with NSURLConnection and the like a bit easier, but if you're doing this from scratch, you're close.
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:#"https://api-ssl.bitly.com/oauth/access_token"]];
The endpoint for Resource Owner Credential Grants. That will get you the access_token you need to access the rest of our API.
The trickiest part of the flow is the "Authorization" header
NSString *authString = [NSString stringWithFormat:#"%#:%#", #"<YOUR CLIENT ID>", #"<YOUR CLIENT SECRET>"];
NSData *authData = [authString dataUsingEncoding:NSUTF8StringEncoding];
NSString *base64 = [authData base64EncodedStringWithOptions:0];
NSString *authHeader = [NSString stringWithFormat:#"Basic %#", base64];
[request setValue:authHeader forHTTPHeaderField:#"Authorization"];
This will set the Authorization field to: Basic clientID:clientSecret correctly base 64'ed
From there you need to set the body to the request
NSString *postBody = [NSString stringWithFormat:#"grant_type=password&username=%#&password=%#", #"<USERNAME>", #"<PASSWORD>"];
[request setHTTPBody:[postBody dataUsingEncoding:NSUTF8StringEncoding]];
Tell the request it's POST
[request setHTTPMethod:#"POST"];
Then open a NSURLConnection and observe the 3 important delegated methods
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[connection start];
You will want to implement:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData*)data
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
Source: I write the Bitly for iPhone app. Hope this helps. Let me know if you have any questions about the API, or the example above.