Reference Type vs Value Type

How do we get to know reference type ?

In Swift , a class or closure or function can be Reference Type.
In Objc, everything inherited from NSObject represents Reference Type.

How do we get to know value type ?

In Swift, we have Structures, Enums and Tuples, along with Int, Double, String, Array, Dictionary, Set as well.
In Objc, Number literals like NSInteger, C structures like CGPoint.

When to use Reference type ?

Comparing two objects those shares the same memory address (aka === )
When you want to create a shared and mutable state

When to use Value Type ?

Comparing instance data with == makes sense.
You want copies to have independent state.
The data will be used in code across multiple threads.

How about memory Allocation ?

Heap memory for reference types.
Stack for Value types.

Linked to similar questions :

Struct vs Class
String vs NSString

(Source-Internet)

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