Swift 5.0 Release - kirseia/study GitHub Wiki

let result = Result { try String(contentsOfFile: someFile) } 

print("<a href=\"\(url)\" title=\"Apple Developer\">")

print(#"<a href="\#(url)" title="Apple Developer">"#)

let answer = 42
let dontpanic = #"The answer to life, the universe, and everything is \#(answer)."#

struct User {
    var name: String
    var age: Int
}

extension String.StringInterpolation {
    mutating func appendInterpolation(_ value: User) {
        appendInterpolation("My name is \(value.name) and I'm \(value.age)")
    }
}

let user = User(name: "Guybrush Threepwood", age: 33)
print("User details: \(user)")

// Swift:
7 % 2 == 1 // true
-7 % 2 == 1 // false. -7 % 2 evaluates to -1
// Ruby and Python
7 % 2 == 1 // true
-7 % 2 == 1 // true

let rowNumber = 4

if rowNumber.isMultiple(of: 2) {
    print("Even")
} else {
    print("Odd")
}

@dynamicCallable struct ToyCallable {
    func dynamicallyCall(withArguments: [Int]) {}
    func dynamicallyCall(withKeywordArguments: KeyValuePairs<String, Int>) {}
}

let x = ToyCallable()

x(1, 2, 3)
// Desugars to `x.dynamicallyCall(withArguments: [1, 2, 3])`

x(label: 1, 2)
// Desugars to `x.dynamicallyCall(withKeywordArguments: ["label": 1, "": 2])`

let id = \Int.self
var x = 2
print(x[keyPath: id]) // Prints "2"
x[keyPath: id] = 3
print(x[keyPath: id]) // Prints "3"

enum X {
    case foo(bar: Int...) 
}

func baz() -> X {
    return .foo(bar: 0, 1, 2, 3) 
} 

enum X {
    case foo(bar: [Int]) 
} 

func baz() -> X {
    return .foo(bar: [0, 1, 2, 3]) 
} 

let a: Set<Int> = [1, 2, 3, 4, 5]
let b: Set<Int> = [1, 2, 3, 4, 5]
a == b  // true
print(a) // [1, 4, 3, 2, 5]
print(b) // [4, 2, 5, 1, 3]

#if swift(<4.2)
// This will only be executed if the Swift version is less than 4.2.
#endif

#if compiler(<4.2)
// This will only be executed if the Swift compiler version is less than 4.2.
#endif

let d: [String: String?] = ["a": "1", "b": nil, "c": "3"]
let r1 = d.filter { $0.value != nil }.mapValues { $0! }
let r2 = d.reduce(into: [String: String]()) { (result, item) in result[item.key] = item.value }
// r1 == r2 == ["a": "1", "c": "3"]

let d: [String: String?] = ["a": "1", "b": nil, "c": "3"]
let r4 = d.compactMapValues({$0})
// r4 == ["a": "1", "c": "3"]

// Swift 4: 'Int??'
// Swift 5: 'Int?'
let result = try? database?.countOfRows(matching: predicate)


// Swift 4: 'String??'
// Swift 5: 'String?'
let myString = try? String(data: someData, encoding: .utf8)
    
// Swift 4: '[String: Any]??'
// Swift 5: '[String: Any]?'
let dict = try? JSONSerialization.jsonObject(with: data) as? [String: Any]

func processImageData(completionBlock: (result: Image) -> Void) {
   loadWebResource("dataprofile.txt") { dataResource in
      loadWebResource("imagedata.dat") { imageResource in
         decodeImage(dataResource, imageResource) { imageTmp in
            dewarpAndCleanupImage(imageTmp) { imageResult in
               completionBlock(imageResult)
             }
          }
       }
    }
}

func processImageData() async -> Image {
    let dataResource = await loadWebResource("dataprofile.txt")
    let imageResource = await loadWebResource("imagedata.dat")
    let imageTmp = await decodeImage(dataResource, imageResource)
    let imageResult = await dewarpAndCleanupImage(imageTmp)
    return imageResult
}