🔸required initializer

╱🚧 under construction -> subclass, override, designated initializer, inherited initializer, convenience init

swift ⟩ type ⟩ init ⟩ initializers ⟩ required

1️⃣ write required before the definition of a class initializer to indicate that every subclass of the class must implement that initializer. ( 👉 💈範例 (1) )

2️⃣ write required before every subclass implementation of a required initializer, don’t write override when overriding a required designated initializer.

You don’t have to provide an explicit implementation of a required initializer if you can satisfy the requirement with an inherited initializer. ( 👉 💈範例 (2) )

💾 語法

// superclass
class SuperClass {
    required init() { ... }    // 1️⃣ required (designated) init
}

// subclass
class Subclass: SuperClass {
    required init() { ... }    // 2️⃣ required init (No `override` here❗️)
}

💈範例

📘 手冊