Identifying Common Legacy Patterns

When working with older Objective-C codebases, you'll often encounter patterns and practices that are no longer common in modern iOS development.

Identifying these legacy patterns is the first step towards understanding, maintaining, and potentially updating the code. It helps you recognize where older memory management, API usage, or syntax might be at play.

Before Automatic Reference Counting (ARC) was introduced, Objective-C developers manually managed memory using a system called Manual Retain-Release (MRR).

• When you create an object, its retain count is 1.
• Calling retain increases the count, indicating another owner.
• Calling release decreases the count.
• When the retain count drops to 0, the object is deallocated.

Seeing explicit retain or release calls is a strong indicator of MRR code.