Using Flattr API v2 with iOS - ios

Question

I'm currently building an iOS application and want to include Flattr-Support over the Flattr-API v2.
I've already created my application at https://flattr.com/apps/ and got the key and secret.
The problem is that I have to provide a callback-URL in the application-settings at flattr even if I select "client" as application type. In addition only http://... callback-URLs seem to be allowed in the input field so I can't set a callback URL to open my application (something like myApp://...)
How do I implement the Flattr oAuth process for client applications?
Are there any detailed instructions how to implement the flattr-authentication with a non-web-based / iOS application?
I planned to use the JDG OAuthConsumer library but this doesn't seem to work - any other iOS librarys I could use?

Answer 1

A short description of my implementation using the Flattr API v2 to flattr a thing from my iOS application:
I'm currently using the "Google Toolbox for Mac - OAuth 2 Controllers":
http://code.google.com/p/gtm-oauth2/
Create a Token to be authenticated:
- (GTMOAuth2Authentication *)flattrAuth {
NSURL *tokenURL = [NSURL URLWithString:#"https://flattr.com/oauth/token"];
// We'll make up an arbitrary redirectURI. The controller will watch for
// the server to redirect the web view to this URI, but this URI will not be
// loaded, so it need not be for any actual web page.
NSString *redirectURI = #"http://localhost/"; //for me localhost with / didn't work
GTMOAuth2Authentication *auth;
auth = [GTMOAuth2Authentication authenticationWithServiceProvider:#"MyApplication"
tokenURL:tokenURL
redirectURI:redirectURI
clientID:clientKey
clientSecret:clientSecret];
return auth;
}
Create a ViewController to authenticate the token:
- (GTMOAuth2ViewControllerTouch*)getSignInViewController{
GTMOAuth2Authentication *auth = [self flattrAuth];
// Specify the appropriate scope string, if any, according to the service's API documentation
auth.scope = #"flattr";
NSURL *authURL = [NSURL URLWithString:#"https://flattr.com/oauth/authorize"];
GTMOAuth2ViewControllerTouch *viewController;
viewController = [[[GTMOAuth2ViewControllerTouch alloc] initWithAuthentication:auth
authorizationURL:authURL
keychainItemName:keychainItemName
delegate:self
finishedSelector:#selector(viewController:finishedWithAuth:error:)] autorelease];
return viewController;
}
and the delegate method:
- (void)viewController:(GTMOAuth2ViewControllerTouch *)viewController
finishedWithAuth:(GTMOAuth2Authentication *)auth
error:(NSError *)error {
if (error != nil) {
DLog(#"Flattr sign-in failed with error: %#", [error localizedDescription]);
} else {
DLog(#"Flattr Signin success");
authToken = [auth retain];
}
}
You can display the Viewcontroller in your application - it displays the flattr-login to the user so he can authenticate the application.
You can flattr a thing with the authentication token this way:
NSString* flattrURL = #"https://api.flattr.com/rest/v2/things/%qi/flattr";
NSURL* u = [NSURL URLWithString:[NSString stringWithFormat:flattrURL, item.flattrThingID]];
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:u];
[authToken authorizeRequest:request completionHandler:^(NSError *error){
if (error == nil) {
// the request has been authorized
NSURLConnection* connection = [[[NSURLConnection alloc] initWithRequest:request delegate:self] autorelease];
if(!connection){
//TODO: handle error
} else {
[connection start];
}
} else {
//TODO: handle error
}
}];
Now implement the NSURLConnectection delegate methods and parse the JSON responses.
The GTMOAuth2 library allows you to save the authenticated token to the keychain. Look at their introduction at http://code.google.com/p/gtm-oauth2/wiki/Introduction#Retrieving_Authorization_from_the_Keychain for instructions.

Answer 2

When you wan't to authenticate a desktop/mobile app you would wan't to use the oauth2 implicit grant flow. As you register your flattr application use a application specific URI that will callback to your application, ex. iphone-application://oauth-callback.
When you authenticate the application with us you use the response_type token instead of code. This will create a token at once and redirect you back to your application.
Ex. request URL: https://flattr.com/oauth/authorize?client_id=2134&redirect_uri=iphone-application://oauth-callback&response_type=token
If the resource owner will authorize your application we will send a HTTP 302 and redirect you back to your redirect uri.
Ex. response 302 Location: iphone-application://oauth-callback#access_token=e5oNJ4917WAaJaO4zvoVV2dt3GYClPzp&token_type=bearer
Currently we don't have any detailed documentation explaining how to do the implicit grant but we are working on the documentation. Meanwhile i'm all ears.
https://github.com/nxtbgthng/OAuth2Client is a iOS oauth2 library but I don't know if it's any good.

Answer 3

This one looks good: https://github.com/neonichu/FlattrKit