Kas saaksite selgitada Retain kontseptsiooni Objective-C-s ja kuidas see mõjutab mälu?

In Objective-C, the retain method is used to manage the lifetime of an object in the reference counting model. When you call retain on an object, you increase its reference count by 1, meaning you take responsibility for keeping it in memory.

This affects memory as follows: the object will not be removed from memory until its reference count reaches zero. To free the object, you need to call release, decreasing the count by 1. When the count reaches zero, the object is deallocated.

Example:

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

Thus, retain helps control the lifetime of objects and prevents premature deletion, but incorrect use can lead to memory leaks.