Any_or_AnyObject_in_Swift.md

created	author	version	license(s)
2024-11-30 22:13:34 -0800	Cong Le	1.0	MIT, CC BY 4.0

Any or AnyObject in Swift

Below is a set of Mermaid diagrams to visually explain Any and AnyObject in Swift.

Diagram 1: Type Hierarchy

This diagram illustrates the relationship between Any, AnyObject, concrete types (like Person, Animal, Int, String, Bool), and bridged Objective-C types (like NSNumber and NSString).

classDiagram
    Any <|-- AnyObject
    AnyObject <|-- Person
    AnyObject <|-- Animal
		AnyObject <|-- NSNumber : Bridged from Int
    AnyObject <|-- NSString : Bridged from String
    Any <|-- Int
    Any <|-- String
    Any <|-- Bool
    Person : +String name
    Animal : +String name
    class Person{
        +init(name: String)
    }
    class Animal{
       +init(name: String)
    }

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Diagram 2: Array Storage

This diagram shows how different types can be stored in arrays of Any and AnyObject, highlighting the bridging behavior.

graph LR
    A[Array of Any] --> B{1}
    A --> C{"2"}
    A --> D[true]
    B --> B1(Int)
    C --> C1(String)
    D --> D1(Bool)

    E[Array of AnyObject] --> F[Person Instance]
    E --> G[Animal Instance]
		E --> H["1 as AnyObject"]
		H --> H1(NSNumber)
    F --> F1(Person Class)
    G --> G1(Animal Class)

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Diagram 3: Type Casting and Identification

This diagram demonstrates how to use is to check types within an Any array and the bridging that occurs when value types are cast to AnyObject.

graph TD
    A[Element in Any Array] --> B{Is String?};
    B -- Yes --> C[String];
    B -- No --> D{Is Int?};
    D -- Yes --> E[Int];
    D -- No --> F{Is Bool?};
    F -- Yes --> G[Bool];
		F -- No --> H{Other Type};

		I[Element in AnyObject Array] --> J{Is Int?}
		J -- Yes --> K[Int]
		J-- No --> L{"Type(of: obj) = NSNumber"}
		L --> M[NSNumber - Bridged]
		

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Diagram 4: Bridging in Detail

This diagram specifically focuses on the bridging process from Swift value types to Objective-C reference types.

graph LR
    A[Swift Int] -- Cast to AnyObject --> B{Bridging}
    B --> C[Objective-C NSNumber]
    D[Swift String] -- Cast to AnyObject --> E{Bridging}
    E --> F[Objective-C NSString]

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