uikit-animation-debugging

Completion handler misfires across devices often stem from CATransaction timing mismatches or frame-rate differences. Diagnose by monitoring CATransaction state, comparing declared versus actual animation durations, and checking layer speed and timeOffset properties to isolate device-specific timing skew.

Compare declared animation duration against actual measured timing by enumerating active animations, inspecting layer state (speed, timeOffset), and analyzing CATransaction wrapping. Device-specific CPU and frame-rate variations often cause perceived timing drift; systematic layer inspection reveals the root cause.

Spring animation timing varies by device frame rate and CPU performance. Diagnose by monitoring layer animation state across devices, comparing CAAnimation properties, and measuring actual versus declared completion timing to establish deterministic patterns for consistent behavior.

Gesture-induced jank typically results from animation timing conflicts or improper CATransaction management. Debug by analyzing active animations, monitoring layer state during gesture events, and ensuring completion handlers fire reliably to prevent frame-rate misalignment.

Simulator testing catches many issues, but device-specific timing skew—caused by varying frame rates and CPU performance—only appears on real hardware. Diagnose completion failures and timing mismatches on target devices to capture true performance patterns before shipping.