swift-protocols

I am trying using extension for an existing class with class method like: @objc public protocol MyProtocol { optional class func foo() -> Int } And I am using this protocol in an extension with generic like: extension MyClass { public func bar<T: MyProtocol>() { ... let x: Int = T.self.foo!() // if I do not use "self" or "!" here, I will have a compiler error ... } This should work but when I build it, Xcode says "Command /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc failed with exit code 1". If I do not use "optional" in the protocol, I do not

So I was playing around with protocol extensions and i ran into an "interesting" problem. I wanted to write a Meters and Kilometers units type for testing some things out. Its VERY easy to do this as a class where there is a base class and both sub classes override the base, while just overriding a simple value //Conversion factor between types enum DISTANCE_UNIT_TYPE : Double { case METER = 1.0; case KILOMETER = 0.001; } protocol DistanceUnit { var unitType : DISTANCE_UNIT_TYPE {get} var value : Double { get set } var baseValue : Double { get set } } struct Kilometers : DistanceUnit { var

I ask a question today because I’m little bit lost today. It’s about Swift and protocol and more about Protocol Oriented Programming (POP). I read articles about it, even a book but I’m still confused. Everybody seems to say that Protocol is a great tool and so on but I don’t really understand its power. I’ve a question because I’m coding a class Volume which is the representation of a volume as an object. Let’s say struct Volume { var value: Float = 1 var isLogScale: Bool = false var maxLogVolume: Float = 6.0 // value in dB var maxLinearVolume: Float = 1.0 let dynamicRange: Float = 50.0 func

I'm playing around with protocols and how to conform to them. protocol Human { var height: Int {get set} } struct boy : Human { var height: Int {return 5} // error! } I'm trying to learn different ways that I can implement set and get. However the code above throws the following error: type 'boy' does not conform to protocol 'Human' However writing as below won't have any errors: struct boy : Human { var height = 5 // no error } I don't understand the difference nor what exactly needs to be implemented when you can also set a variable. I looked into different questions and tutorials but they

I'd like to write an extension for tuples of (e.g.) two value in Swift. For instance, I'd like to write this swap method: let t = (1, "one") let s = t.swap such that s would be of type (String, Int) with value ("one", 1) . (I know I can very easily implement a swap(t) function instead, but that's not what I'm interested in.) Can I do this? I cannot seem to write the proper type name in the extension declaration. Additionally, and I suppose the answer is the same, can I make a 2-tuple adopt a given protocol? You cannot extend tuple types in Swift. According to Types , there are named types

I've the following code: protocol NextType { associatedtype Value associatedtype NextResult var value: Value? { get } func next<U>(param: U) -> NextResult } struct Something<Value>: NextType { var value: Value? func next<U>(param: U) -> Something<Value> { return Something() } } Now, the problem is in the Something implementation of next . I want to return Something<U> instead of Something<Value> . But when I do that I got the following error. type 'Something<Value>' does not conform to protocol 'NextType' protocol requires nested type 'Value' ghashi I tested the following codes and they

I have been struggling very hard with Swift Protocols and Associated Types for a long time. I started again with basic to really understand what is going wrong and I followed this article of TypeErasure in Swift Protocols with Associated Type Requirement by Rob Napier but still i have no luck. Find the code below // An Animal can eat protocol Animal { associatedtype Food func feed(food: Food) -> Void } struct AnyAnimal<Food>: Animal { private let _feed: (Food) -> Void init<Base: Animal where Food == Base.Food>(_ base: Base) { _feed = base.feed } func feed(food: Food) { _feed(food) } } // Kinds