Measuring FPS/Performance in Xcode/Iphone
You can use instruments for this! Tap and hold the play button in Xcode and press 'profile' and it will open the instruments app. Use the Core Animation Template. It'll show you FPS to test your scroll performance.
You can also use this tool for measuring FPS on both iOS and Android devices, simultaneously and you dont even need a mac (PC/linux would do!)
https://www.gamebench.net/en/content/gamebench-desktop-profiler