Is it worth to bother with iPhone 4 when developing a new application? I'm currently working on an iOS application which almost started from scratch (And I did also as I didn't work on iOS before that).
My question is : Now that we have iOS8 that is to replace iOS7 and iPhone6 should I bother make my display compatible with iPhone 4 ?

I've try to look for statistics on the web but I wasn't very lucky and couldn't find any numbers to help me take a decision... What is really frustrating is that some of the very useful library don't work on iOS8 (or at least not like they're supposed to...) But work like charme on iOS7.

If anyone has some knowledge to share... More than welcome !

Thanks
You're going to run into trouble if you try to make your application code device-specific. The correct way to approach a software release is to target OS-compatibility. That means that if you're going to go for a minimum of iOS 7, you need to ensure that your software is compatible with all the devices that are able to run that iOS version. Anything else opens you up to a whole world of hurt. App Store does NOT define system requirements by device model.