ios-performance

Memory leaks occur when objects remain in memory after they're no longer needed, often due to retain cycles. Use Instruments' Allocations and Leaks tools to detect growth patterns, then trace references to find circular dependencies between objects and break them by weakifying captures or delegates.

Battery drain stems from excessive CPU usage, frequent network requests, and continuous location tracking. Profile energy impact with Instruments' Energy Impact tool to identify hot spots, then reduce background activity, batch network calls, and optimize sensor usage.

Instruments captures real-time CPU, memory, and I/O metrics during app execution. Use the System Trace and Core Animation tools to isolate slow function calls and frame drops, then correlate spikes with code sections to pinpoint bottlenecks causing sluggish performance.

Yes, Instruments attaches to running apps on device or simulator without requiring changes to source code. Profile live performance metrics including memory allocations, CPU cycles, and energy draw to diagnose issues in your actual release or debug builds.

Memory leaks are permanent unreleased objects; gradual growth indicates accumulating allocations over time, often from caches or retained temporary objects. Instruments' Allocations tool shows both patterns—leaks spike sharply, while growth climbs steadily and may stabilize.

Retain cycles with blocks occur when self captures the enclosing object, preventing deallocation. Break cycles by capturing self weakly in closures or using unowned references when the object outlives the block, verified through Instruments' heap analysis.