whats-new-in-swift-4.2

whats-new-in-swift4.2.swift

// SE-0194 Derived Collection of Enum Cases
enum CarType : CaseIterable {
    case sedan
    case crossover
    case hothatch
    case muscle
    case miniVan
}

print(CarType.allCases.count)

//Conditional Conformance

let arrayOfArrays = [[1,2],[3,4],[5,6]]

arrayOfArrays.contains([1,2]) // now it returns True because of fact that the elements in the array conforms to Equatable protocol

let s: Set<[Int?]> = [[1,nil,2], [3,4], [5, nil,nil]]
s.contains([1,nil,2]) // returns true

// Hashable protocol

struct City {
    let name: String
    let state: String
}

extension City : Hashable {
    func hash(into hasher: inout Hasher) {
        name.hash(into: &hasher)
        state.hash(into: &hasher)
    }
}

let warsaw = City(name: "Warsaw", state: "Mazowieckie")
let cracow = City(name: "Kraków", state: "Małopolskie")

print(warsaw.hashValue)
print(cracow.hashValue)

// Generating Random numbers

let randomIntFrom0To20 = Int.random(in: 0 ..< 20)
let randomFloat = Float.random(in: 0 ..< 1)
let names = ["John", "Paul", "Peter", "Tim"]
names.randomElement()! // you need to unwrap the randomElement, because of the case where we call `randomElement` on empty collection.

names.shuffled()

let playerNumberToName : [Int: String] = [9: "Lewandowski", 7: "Ronaldo"]
playerNumberToName.randomElement()

let emptyCollection : [String] = []
emptyCollection.randomElement() // retuns nil

// Bool toggle

var isTheWeatherNice : Bool = true
print(isTheWeatherNice)
//now it's starts to rain
isTheWeatherNice.toggle()
print(isTheWeatherNice)