I believe a lot of people have heard of and even used three20 library for building their apps. What's the pros and cons of using it? what's your experience so far - starting from ramping up, app design, building, to approval, and future maintains...
I am interested in picking it up, attracted by the UI elements that not easily get from the official SDK.
I used it for a few time. The main con is that you must develop the entire project with the three20 library else some bugs will appear.
I've started developing a new app with Three20. Little note: I've started iPhone Development about one year ago. I was attracted by the UI elements too, so i thought I'll give it a try.
Downloading the source is strait forward, but when it comes to integrating Three20 to an App it gets difficult. I think I've need about half a day to get it running. The big problem was, that I'm using XCode 3.2.3 with iOS SDK 4.0 and the source I've downloaded was set to run on iOS 3.2. After I read a lot of blog-posts and stuff like that, I finaly managed to run my app on the Simulator and on Device.
The next steps were kind of easy. You can use the UI-Elements and Core-Functions of Three20 easily. Build your app using the URL-based-navigation is great. So Three20 does at lot of things you normaly have to care of yourself. E.g. normaly you have to alloc and init your ViewController, push it to your NavigationController and release it. In Three20 you only have to "call a URL" and the rest is done by the library.
From this point of view Three20 is really great. The next problems I faced was, when you want to customize or change the standard-build-in-components. I've spend a lot of time reading through the class documentation on Three20.info until I've managed to build my own TableCell. I've faced the same Problem, when I want to load my data a different way to a TableView.
Until now I haven't got any problems with some other libraries in the same project.
I think Three20 is great and easy. On the other side it can be quite difficult. If you like the UI Elements, you should give it a try.
The main problem with Three20 is you have to take all of it or none of it - you can't easily just choose a part you'd like to use.
It's worth searching out other projects that do things you might want Three20 for - like photo browsing.