Why is Xcode 7 iOS Simulator freezing?


Question or issue on macOS:

I’m getting odd freezes of up to 60s in the Xcode 7 simulator, specifically when scrolling or doing other GPU-intensive tasks. The problem appears to be with the simulator as a whole, not my app (lots of spinning beach ball, slow to respond to rotate commands, etc.).

If I track CPU time in Instruments, 50s of real time shows as below 0.5s of CPU time for my app.

What’s going on? (El Cap, Xcode 7.1, all iOS versions, all devices)

How to solve this problem?

I run Better Snap Tool for window management. Quitting this app (or disabling it from interacting with the simulator) fixes the problem immediately, even if the sim is in the middle of a freeze. No idea why, but Better Snap Tool appears to be interfering with iOS Simulator’s use of the GPU.

Hope this helps!