01. Cases of Structures

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Swift › 03. Structs

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1. Use structures when you’re modeling data.

Use structures when you’re modeling data that contains information about an entity with an identity that you don’t control. For example:

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struct PenPalRecord {
    let myID: Int
    var myNickname: String
    var recommendedPenPalID: Int
}
var myRecord = try JSONDecoder().decode(PenPalRecord.self, from: jsonResponse)

2. Use Structures and Protocols to Model Inheritance and Share Behavior.

Structures and classes both support a form of inheritance. Structures and protocols can only adopt protocols; they can’t inherit from classes. However, the kinds of inheritance hierarchies you can build with class inheritance can be also modeled using protocol inheritance and structures.

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protocol AnimalCommonProtocol {
    var name: String? { get set }
    var weight: Double { get set }
    func run()
}

struct Cat : AnimalCommonProtocol {
    func run() {
        print("cat run")
    }
    var name: String?
    var weight: Double
    var gender: String?
}

struct Dog : AnimalCommonProtocol {
    func run() {
        print("dog run")
    }
    var name: String?
    var weight: Double
    var type: String?
}