Can you explain how Retain and Release work in memory management?

Memory management in iOS is often based on reference counting. The retain and release methods are used to increase and decrease the reference count of an object.

• retain increases the reference count, indicating that another part of the code owns the object.
• release decreases the reference count, signaling that the part of the code no longer needs the object.

When the reference count reaches zero, the object is automatically destroyed and memory is freed.

Example in Objective-C:

NSObject *obj = [[NSObject alloc] init]; // reference count = 1
[obj retain]; // reference count = 2
[obj release]; // reference count = 1
[obj release]; // reference count = 0, object is deleted

Modern iOS uses ARC (Automatic Reference Counting), which automatically inserts calls to retain and release during compilation, freeing developers from manual memory management.