An implementation of MPOAuth that actually works on iOS. Thanks for Carl Adam for making the otherwise awesome MPOAuth library. License: CreativeCommons Attirbution Unported 3.0 License

How to use this stuff:

1. Create an instance initted to a. either one of the default/recognized base URLs (examples: twitter, yahoo, google, foursquare etc. see MPOAuthServiceProviderConfiguration.plist) or b. a base URL and an auth URL:

   import <MPOAuth/MPOAuth.h>

NSDictionary appCredentials = [NSDictionary dictionaryWithObjectsAndKeys:@"ApPcOnSuMeRkEy", kMPOAuthCredentialConsumerKey, @"OAuthApPsEcReTkEy", kMPOAuthCredentialConsumerSecret, nil]; MPOAuthAPI client = [[MPOAuthAPI alloc] initWithCredentials:appCredentials andBaseURL:[NSURL URLWithString:@"https://api.twitter.com/"]]; client.delegate = self; // e. g. your view controller

2. In your delegate, provide the callback URL to the API. This will be passed along with the OAuth access token & secret when the user authorizes your app.

• (NSURL ) callbackUrlForOAuthApi:(MPOAuthAPI )api { NSURL *url = [NSURL URLWithString:@"myapp-oauth-callback://twitter"]; return url; }

3. When you need the OAuth access, check if you've already got it; if not, start the dance:

   if ([client isAuthenticated]) { // do whatever you want * } else { [client authenticate]; } }

Now the client will acquire the request token, then it will open the authentication URL in Safari. When the user authorizes your app, the service (hopefully) will redirect him/her to your app via the custom URL scheme along with the request token & secret & verifier (myapp-oauth-callback://twitter?oauth_token=sOmEOAuthToKeNyOuGoT&oauth_token_secret=wHaTeVeRrAnDoMsTuFf&oauth_verifier=vErIfIeR) You'll need to handle this in your application:handleOpenURL: method in your app delegate, as the following:

• (BOOL) application:(UIApplication )sharedApplication handleOpenURL:(NSURL )openUrl { // check whether or not it's an OAuth callback redirect URL if ([[openUrl scheme] isEqualToString:@"myapp-oauth-callback"]) { // OAuth callback!!! parse the parameters NSDictionary *params = [MPURLRequestParameter parameterDictionaryFromString:[openUrl query]] // params now contains the oauth_token and oauth_token_secret, so pass it on the OAuth API instance [client setCredential:[params objectForKey:@"oauth_token"] withName:MPOAuthCredentialAccessTokenKey]; [client setCredential:[params objectForKey:@"oauth_token_secret"] withName:MPOAuthCredentialAccessTokenSecretKey]; // (**) [client setCredential:[params objectForKey:@"oauth_verifier"] withName:MPOAuthCredentialVerifierKey]; // and let it know that it needs to conitnue the dance [client authenticate]; // yes, the same method again } else { // some other things happened, unrelated to OAuth [self doSomethingWithThe:openUrl]; } return YES; }

3. If you've done this, the API will ask the service for the access token and then notify you that it got the tokens in it's delegate's oauthApi:receivedAccesToken:secret: method. The API will smartly store the tokens, so you don't have to authorize it when your app has to be restarted. You can log out using [client discardCredentials]; after.

• To actually do something useful with the API/client, you'll need to perform either GET or POST methods to the API's resource URLs, with the proper parameters (abstractly implemented by the MPURLRequestParameter class - it creates an array of parameter objects from a GET-format URL query string): For example, you do so to update a user's status on Twitter: [client performPostMethod:@"/1/statuses/update.json" withQuery:@"status=Just updated my status using OAuth 1.0a!" target:self action:@selector(updatedStatus:response)];

and in the delegate:

• (void) updatedStatus:(MPOAuthAPIRequestLoader )ldr response:(NSString )response { UIAlertView *av = [UIAlertView new]; av.title = @"Tweet sent"; av.message = response; // JSON [av addButtonWithTitle:@"Dismiss"]; [av show]; [av release]; }

Well, that's all you need to know about MPOAuthAPI.

TODOs:

• support multipart/form-data methods for POST methods to enable uploading files (images to Twitter, sound files to soundcloud etc.)
• Implement JSON- and XML-parsing to pass nice Cocoaized parameters to our delegate