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About Protocols A Protocol specifies initialisers, properties, functions, subscripts and associated types required of a Swift object type (class, struct or enum) conforming to the protocol. In some languages similar ideas for requirement specifications of subsequent objects are known as ‘interfaces...
Protocols may define associated type requirements using the associatedtype keyword: protocol Container { associatedtype Element var count: Int { get } subscript(index: Int) -> Element { get set } } Protocols with associated type requirements can only be used as generic constraints:...
A delegate is a common design pattern used in Cocoa and CocoaTouch frameworks, where one class delegates responsibility for implementing some functionality to another. This follows a principle of separation of concerns, where the framework class implements generic functionality while a separate dele...
You can write the default protocol implementation for a specific class. protocol MyProtocol { func doSomething() } extension MyProtocol where Self: UIViewController { func doSomething() { print("UIViewController default protocol implementation") } } class M...
// RawRepresentable has an associatedType RawValue. // For this struct, we will make the compiler infer the type // by implementing the rawValue variable with a type of String // // Compiler infers RawValue = String without needing typealias // struct NotificationName: RawRepresentable { ...
A protocol may specify that only a class can implement it through using the class keyword in its inheritance list. This keyword must appear before any other inherited protocols in this list. protocol ClassOnlyProtocol: class, SomeOtherProtocol { // Protocol requirements } If a non-class typ...
Types used in Sets and Dictionaries(key) must conform to Hashable protocol which inherits from Equatable protocol. Custom type conforming to Hashable protocol must implement A calculated property hashValue Define one of the equality operators i.e. == or !=. Following example implements Hasha...

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