Question

I am building a cocos2d continuous running ios game, where a character is animated to run through a scene. The background, the grounds under the character’s feet and a fence behind the running character move in the opposite direction to simulate forward motion. The character itself is animated to run in place. Occasionally additional sprites move by in the scene.

All my movement (except the in place animation of the character) happens in the update method.

I notice that all the moving parts stutter when additional sprites are moving past the scene. When there are no additional sprites, the stutter goes away.

I also notice that the stutter is almost imperceptible in the ipad 3 (ios 6.0.1), whereas it is most noticeable in the iphone 3gs (ios 6.0.1) and ipad 1 (ios 5.1.1), and moderately noticeable on the iphone 4 (ios 6.0.1).

I have no idea where to begin to address this – I tried removing the actual rendering of the additional sprites, and I also tried removing the fence behind the character – but neither change had any impact on the stutter.

Any suggestions?

Update: fixed it by running time profiler as @Fogmeister suggested below. Turns out I was doing disk i/o on every update to look up some state variables. I optimized that away and the stutter is gone on all devices. Thanks!

Answer 1

You need to identify what is taking up the time in the code and causing the stutter.

It seems like it is just an optimisation issue as you can see more stutter on older, slower devices and less on new more powerful devices.

Analyse the app using the Time Profiler instrument. This will tell you where the time is being spent and point you almost instantly to the function (if not the line) that is taking the time.

Once you’ve found that you can start optimising.