What is the difference between classes and structures in Swift?

In Swift, classes and structures are two different data types used for storing and manipulating data. The main differences between them are as follows:

1. Inheritance: Classes can inherit the characteristics and behaviors of other classes, while structs do not support inheritance.
2. Reference type versus value type: Classes are reference types, while structures are value types. When a class is assigned to a variable or passed to a function, it is actually passing a reference to the variable or function, allowing multiple variables or functions to reference the same instance of the class. On the other hand, structures are value types; when a structure is assigned to a variable or passed to a function, it creates a copy of that structure, so each variable or function has its own instance of the structure.
3. Memory management: As classes are reference types, memory management is handled by ARC (automatic reference counting). In contrast, structures are value types and are allocated memory on the stack, eliminating the need for manual memory management like classes.
4. Mutability: Instances of classes can be defined as either constants or variables, while instances of structures are always mutable.
5. Type conversion: Classes can use type conversion to check and interpret the type of their instances. Structures do not support type conversion.

In general, when you need a data type with inheritance and complex functionality, you should use a class. And when you need a simple, value type data structure, you can use a structure. Choose between using a class or structure based on your specific needs.