Is testing an app with only an iOS 5 device and iOS 4 simulator OK?

Question

I've recently upgraded my Xcode version and have been having huge trouble trying to build to my 2nd gen iPod Touch running iOS 4.2.1. - So much so that I've given up attempting.

Building to the simulator works fine for the iOS 5 and iOS 4.2 simulators - I'm also going to test the app on an iOS 5 device (when I get my hands on one).

Is this testing sufficient to release an app that has a minimum iOS of 4.2.1? - The problem is I've already released the app which has a minimum iOS of 4.2.1, but I need to release this update (without testing on an iOS 4 device).

Are there any issues with doing this? - If it works on an iOS 4 simulator and iOS 5 simulator/device is that good enough?

Answer 1

No, the simulator is a simulator and not good enough for testing an app.

The differences between simulator and device are, from my experience, rich in number and severity. I would never release an app without testing it on the actual device. Whenever I release an app that also should be compatible with iPhone 2G/3G etc., the actual testing on those devices always results into issues I never encountered on the simulator.

One great example for a common trap when rendering ARM6 compatible code is a bad bug of LLVM2 and 3. This will generate faulty optimized code for this architecture. The connected issues will however only be visible on the actual device and not on the simulator (as that baby uses x86 code and not ARM6).