Where is data type information stored in Swift?

Type metadata in Swift stores information about data types.

Type metadata contains the following details:

• Size of the type.
• Memory alignment of the type.
• Stride (distance between elements in an array).
• Type properties (for example, for classes and structures).
• Type methods.
• Protocols that the type conforms to.
• For classes: superclass, information about the virtual table (vtable).

Access to metadata is done through type(of:) or .self for a specific instance or type.

// Getting the type of an instance
let name = "Swift"
let typeOfName = type(of: name) // String.Type

// Getting the type of a class
let myClassType = MyClass.self // MyClass.Type

// Examples of using metadata
struct MyStruct {
    var value: Int
}

let metadata = type(of: MyStruct.self)
// print(MemoryLayout<MyStruct>.size) // Size of the type, often matches the information in the metadata