I have a project where it rotates 2 spindles 360 degrees both at different speeds over time. I have noticed that it runs well on simulator but when I test it on a device it is significantly slower. The timing taken to make the first 3 full rotations on the simulator and the device are:
On Simulator: 7.0, 7.2, 7.2
On Device: 19.3, 19.5, 19.7
Essentially the project works but I’d like to find out why there is such a big difference between device and simulator and I thought CGContextRotateCTM might be the source.
Sounds right.
Don’t forget, when you run the simulator, you are actually compiling native code to run on your native x86 hardware. Assuming your Mac runs faster than the 800MHz ARM chip in the iPhone – no surprise it will run faster in the simulator.
If you need deterministic timing in your application, your going to need more work to achieve that. This is where people use things like the UIView animation timing, NSTimer calls, or cocos2d inter-frame timers to give deterministic time to their animation calls.
If you don’t – when the next gen device comes out with a faster CPU – your app will again be messed up.
Remember when they used to have “Turbo” buttons on PCs to deal with this?! :-O