An Objective-C library implementing OAuth protocol and some Twitter convenience methods, and an example iPhone app demonstrating its use.
Jaanus Kase, http://www.jaanuskase.com
I have tested the example app in Xcode 3.2.3 on iPhone with iOS 4, and iPad with iOS 3.2. It runs fine both on simulator and the devices. It may not work on earlier iPhone OS-es below 3.0.
A number of changes supporting the longer-term goals of adding other example OAuth providers besides Twitter, and moving the project to ARC model.
Note that there are a few things you must do to make sure your URL callback-based flow works.
All of the above is demonstrated in the PlainOAuth example app.
Re-enable the "get PIN" link if token request fails.
Now sending "oauth_callback=oob" parameter when requesting the original token, per Twitter’s recommendation. (http://twitter.com/episod/status/20722145979)
Fixed a double-encoding problem in OAuth authorization header. (Thanks Chris Burkhardt.)
Profile image upload example. Twitter returns a 200 OK response, but the image does not actually show up, possibly due to a bug in Twitter servers. See this and this Twitter API discussion thread for updates.
UI detail: Twitter status field now resigns first responder after each post or when you press some other button in the UI, so you could see the controls below.
Demo of image uploading to TwitPic with OAuth Echo authentication.
A major rewrite. The OAuth core has not changed, but the example app has gotten a major rewrite and is now much easier to read. I tried to make the architecture more approachable.
Universal app. The app now works on iPhone and iPad, and supports both landscape and portrait modes. Getting the rotations and UI to work reasonably well took me longer than expected, but the end result seems to be quite approachable.
Embedded browser. The previous example took you out of the app and into Safari to get the PIN. While secure, this experience was sub-par. The new version uses an embedded UIWebView to load the PIN from Twitter.
Better designed reference login UI. The login UI is not a random hack anymore; it actually has some design and layout. I took the login UI from Crème and am hereby releasing it to public use. Feel free to use it in your own apps.
GET example. Doing GET with OAuth may be tricky and I got some questions about it, as you have to give OAuth the normalized URL and parameters separately, yet you merge them when constructing your actual HTTP request. This example should take away some confusion.
Refactored delegates. TwitterLoginPopup now uses two delegates: delegate
Subclassing note: you may want to subclass TwitterLoginPopup similarly as is done in this app. Some of the things you could then do are to set the navigation title bar tint, override shouldAutorotateToInterfaceOrientation: if you only support some particular rotations in your app, and incorporate some UI element for progress feedback as is done here with a very basic activity indicator.
Initial release.
I wanted to learn more about the OAuth protocol: specifically how to implement it in Objective-C and how to use Twitter with OAuth. I looked at some other libraries, but they felt too bloated for me. They overloaded NSURLRequest and/or some Twitter library in all sorts of weird ways.
I want my apps to use independent, focused libraries. This library therefore ONLY implements the basic OAuth signature and header generation; no more, no less. Additionally, it is right now somewhat coupled to Twitter, and contains some convenience methods for working with Twitter. Making it work with some other OAuth provider may need some decoupling.
This is also a learning project for me to understand how to architect your app around OAuth, as well as how to develop universal apps and portrait+landscape layout support with the least effort.
For a simple REST GET request for no parameters, all you need is this (assuming you already have an authorized token):
#import "OAuth.h"
OAuth *oAuth = [[OAuth alloc] initWithConsumerKey:myKey andConsumerSecret:mySecret];
oAuth.oauth_token = a_previously_obtained_and_authorized_token;
oAuth.oauth_token_secret = a_previously_obtained_and_authorized_secret;
oAuth.oauth_token_authorized = YES;
NSString *requestHeader = [oAuth oAuthHeaderForMethod:@"GET" andUrl:@"http://example.provider/example/command" andParams:nil];
[myHttpLibrary addHeaderValue:requestHeader forHeader:@"Authorization"];
[oAuth release];These let you easily complete the authentication sequence:
[oAuth synchronousRequestToken];
[oAuth synchronousAuthorizeTokenWithVerifier:<pin you got from user>];See OAuth.h, OAuth.m and the example app for a complete example.
If you use the Twitter convenience methods, all HTTP calls are synchronous. This lets you do threading in a way that you like most yourself. The example app shows one possible approach.
If you copy PlainOAuth code to your app, make sure you have the following frameworks added to your project.
Here are three posts on the background of this, that may help you understand this code better.
New version of PlainOAuth, the example Twitter OAuth app for iPhone
Understanding the guts of Twitter's OAuth for client apps
An example iPhone Twitter app with OAuth authentication
I use the work of several others:
OAuth Consumer by Jon Crosby. I have included some code from this project, specifically NSString URL-encoding, base64 and crypto. There is an "iPhone-ready" version of this library here.
ASIHTTPRequest for HTTP. This is only for example app and Twitter convenience methods; the core OAuth implementation does not do HTTP. (I used this library in the earlier versions of PlainOAuth. I am trying to cut down the dependencies other than Apple core libraries and am no longer using ASIHTTPRequest.)
Tweepy. This is a nice Twitter API implementation in Python (including OAuth) that was helpful in understanding the protocol.
Stack Overflow has been invaluable to me in learning about miscellaneous iPhone development.
Copyright (c) 2010 Jaanus Kase
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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