iPhone device vs. iPhone simulator

Question

I have heard of apps not working properly on the simulator but working properly on the actual iPhone device. Has anyone experienced an app that runs perfectly in the simula

Answer 1

movie file (m4v type) as my exprience is first time playing properly

but at second time it flickers screen of simulator...

whereas in iPhone device it works fime...

Answer 2

Without considering the performance differences between the two, there used to be some things that the simulator didn't do correctly - i.e. it would mess up audio in some cases (see this question). However since the 2.2 SDK this issue has been resolved and the sound seems to be fine in the simulator. That's not to say that there is some other incompatibilities lurking down there! (Just none I've run into)

Answer 3

iphone video library is not accessible in simulator but code work fine on actual device

Answer 4

There are certain bits of code that won't work on the simulator (using the iPhone Keychain, for example), but for almost all applications, the simulator will work exactly like the iPhone.

That said, there's absolutely no replacement for testing on a real device.

Answer 5

Trigonometry functions may return different results:

float a = cosf( 0.108271248639 );   
printf("%.12f", a);

//simulator: 0.994144439697
//device:    0.994144380093

Answer 6

I know there are some differences in the OpenGL ES implementation between the device and the simulator. From what I understand this is mainly because of the graphics chip on the iPhone (PowerVR MBX) having vastly different capabilities than other mac machines. Many of the hardware limits are not enforced in the simulator, so it is entirely possible to get something running in the simulator that will totally crash on the device.

There are also some OpenGL ES extensions that are supported by the iPhone hardware that are not supported in the simulator. I believe the major one is PowerVR texture compression (PVRTC).

Another problem area can be memory footprint. Anecdotally, I have not seen the simulator automatically enforce the memory limitations of the device. Therefore, it is possible to have something that runs in the simulator fine, happily consuming copious amounts of RAM and never bothering to free any of it only to be swiftly terminated after a short continuance of such behaviour when running on a device.