iOS 5 Twitter Integration with soft fallback

After the introduction of Twitter support to iOS 5, it has become really difficult to find reasons not to add it to your app. Indeed, Apple made adding Twitter to your app really a snap. As you can find out from several sources on the web, all that is needed is:

1. Importing the relevant header files into your .m file

[sourcecode]
#if defined(__IPHONE_5_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_5_0
#import <Twitter/Twitter.h>
#import <Accounts/Accounts.h>
#endif
[/sourcecode]

Notice how the import is guarded, so that it only occurs when you are compiling in an Xcode version that supports SDK 5. Once you have done that, the next step is:

2. Adding the code to tweet

[sourcecode]
– (IBAction)tweet:(id)sender {

Class tweeterClass = NSClassFromString(@"TWTweetComposeViewController");
if (tweeterClass != nil && [tweeterClass respondsToSelector:@selector(canSendTweet)]) {
UIViewController *twitterViewController = [[tweeterClass alloc] init];

[twitterViewController performSelector:@selector(setInitialText:) withObject:@"Check This Wonderful APP"];
[self presentModalViewController:twitterViewController animated:YES];
[twitterViewController release];
}
}
[/sourcecode]

Notice how the tweet has the form of an event handler that you can associate to tapping on a button. Also, notice how the use of NSClassFromString and performSelector allows to avoid having to guard this code against compilation or execution when iOS 5/SDK 5 is not there. This code will simply work.
The example above shows a very basic use of the Twitter framework. You could as easily add more juice by providing an image and a URL for your tweet, like in the following:

[sourcecode]
– (IBAction)tweet:(id)sender {

Class tweeterClass = NSClassFromString(@"TWTweetComposeViewController");
if (tweeterClass != nil && [tweeterClass respondsToSelector:@selector(canSendTweet)]) {
UIViewController *twitterViewController = [[tweeterClass alloc] init];

[twitterViewController performSelector:@selector(setInitialText:) withObject:@"Check This Wonderful APP"];
[twitterViewController performSelector:@selector(addURL:) withObject:[NSURL URLWithString:url]];
[twitterViewController performSelector:@selector(addImage:) withObject:urImage];
[self presentModalViewController:twitterViewController animated:YES];
[twitterViewController release];
}
}
[/sourcecode]

Once you have your twitter code in place, do not forget the last step:

3. Adding Twitter and Accounts Frameworks to your project

This goes without special need for explanations.

The only point worth noting is that you need making those frameworks optional, like in the picture here, if you want your app run also on iOS version previous to iOS 5.

At this point, you have Twitter integrated. Really easy.
The only problem left is: what to do with previous versions of the iOS SDK, which did not offer Twitter integration?

There are several options. One is supporting Twitter through MGTwitterEngine by Matt Gemmell, or ShareKit. Actually, ShareKit offers many more possibilities of integration with sharing and social services out there, so you might have a look at it beyond the need for Twitter integration.

Anyway, integrating MGTwitterEngine or ShareKit, though not difficult, is slightly more complex than what you need to do to natively support Twitter in iOS 5. Mostly, the complexity comes from having to handle the oAuth protocol, obtaining a Key from Twitter for your app and so on.

So, what I am suggesting in this post is defining a soft fallback strategy for your app:

1. full Twitter support under iOS 5;
2. soft fallback in previous iOS versions.