What is a memory leak

Generated on 9/6/2024

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A memory leak occurs when memory that is no longer needed by a program is not released back to the system. This typically happens when the last pointer to a block of memory is lost, making the memory unreachable and unable to be used again. There are three types of memory on the heap:

  1. Useful Memory: Memory that is reachable and will be used again.
  2. Abandoned Memory: Memory that is reachable but will not be used again, contributing to the app's footprint unnecessarily.
  3. Leaked Memory: Unreachable memory that cannot be used again, often due to lost pointers or reference cycles.

To address memory leaks, developers aim to find and fix references in cycles, which might involve removing accidental references or changing ownership qualifiers from strong to weak or unowned. Tools like Xcode's memory graph debugger and Instruments can help identify and resolve these issues.

For more detailed information on memory leaks, you can refer to the session Analyze heap memory (20:15).

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Analyze heap memory

Analyze heap memory

Dive into the basis for your app’s dynamic memory: the heap! Explore how to use Instruments and Xcode to measure, analyze, and fix common heap issues. We’ll also cover some techniques and best practices for diagnosing transient growth, persistent growth, and leaks in your app.