Arguably, the easiest way to make a "quick" iphone app, is to write a web app with a UI optimized for mobile and put it on a server and give out the URL. The app won't feel quite like a native app, it won't be able to run background tasks, each time you run it, it'll probably need to load all of the resources, but it's a great way to quickly test your concept, it'll work on all mobile platforms, and you won't have to get it approved by an app store.
Agreed, and if getting it into the App Store was a requirement, wrapping a functional "Web App" in something like PhoneGap is probably the easiest thing you'll ever do using Xcode.
Arguably, the easiest way to make a "quick" iphone app, is to write a web app with a UI optimized for mobile and put it on a server and give out the URL. The app won't feel quite like a native app, it won't be able to run background tasks, each time you run it, it'll probably need to load all of the resources, but it's a great way to quickly test your concept, it'll work on all mobile platforms, and you won't have to get it approved by an app store.