What is MetricKit and how do you collect performance metrics from real devices?
Essence
Instruments shows how the app behaves on your device in your scenario. Users, though, run it on old phones, with a bad network, full memory and in the heat. MetricKit (iOS 13+) collects aggregated performance metrics and diagnostics on their devices and hands them to the app about once a day — from there you send them to your own analytics. Xcode Organizer shows similar data for all users who agreed to share analytics with developers.
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