I am working on a game for iOS 9+ using SpriteKit framework and Xcode 7.3.1. Currently my app suffers slight frame drops from 60 to about 57 from time to time without a clear pattern; which causes nasty glitches. First I thought it happens due to audio effects I am playing, but it's definitely not the only cause.
What instruments and technique would you recommend me to further analyse this problem?
It would be nice to see a hierarchy of the called functions in all threads at the point in time the frame rate drops. I know from other IDE's that there exist analyser tools that show time consumption for individual function calls. Is there anything similar for Xcode?
The tool you want is Instruments. Use the "Core Animation" template, which will have the two instruments you want ("Core Animation" and "Time Profiler").