Are there any libraries similar to Three20? Three20 does not work for me on iOS 5; it gives me warnings. Three20 provides powerful view controllers such as the Launcher, the popular Photo Browser, and internet-aware tables. The library is modular, meaning you choose which elements of the library to include in your app. This modular design allows Three20 to be one of the only Objective-C frameworks that encourages what are called 'extensions' from the community.