What are memory leaks?

Memory leaks are situations where a program allocates memory to store data but then forgets to free it after use. As a result, this memory remains occupied even when it is no longer needed, leading to increased memory consumption over time and potentially causing slowdowns or crashes.

In iOS, memory leaks are often related to improper management of object references, such as when objects reference each other (retain cycles), and ARC (Automatic Reference Counting) cannot automatically free them.

Example of a retain cycle in Objective-C:

@interface Person : NSObject
@property (strong, nonatomic) NSString *name;
@property (strong, nonatomic) Person *friend;
@end

// If personA.friend = personB and personB.friend = personA, the objects hold each other, and memory is not released.

Tools like Instruments in Xcode with the Leaks profile are used to detect leaks.