Swift语言代码格式规范样例

代码来源于：《The Swift Programming Language Swift 4.2》

for循环 | if语句 | switch语句

for score in individualScores {
    if score > 50 {
        teamScore += 3
    } else {
        teamScore += 1
    }
}

switch vegetable {
case "celery":
    print("Add some raisins and make ants on a log.")
case "cucumber", "watercress":
    print("That would make a good tea sandwich.")
case let x where x.hasSuffix("pepper"):
    print("Is it a spicy \(x)?")
default:
    print("Everything tastes good in soup.")
}

for score in individualScores {

if score > 50 {

teamScore += 3

} else {

teamScore += 1

}

switch vegetable {

case "celery":

print("Add some raisins and make ants on a log.")

case "cucumber", "watercress":

print("That would make a good tea sandwich.")

case let x where x.hasSuffix("pepper"):

print("Is it a spicy \(x)?")

default:

print("Everything tastes good in soup.")

}

函数 | 闭包

func greet(_ person: String, on day: String) -> String {
    return "Hello \(person), today is \(day)."
}
greet("John", on: "Wednesday")

let mappedNumbers = numbers.map({ number in 3 * number })
print(mappedNumbers)

func greet(_ person: String, on day: String) -> String {

return "Hello \(person), today is \(day)."

}

greet("John", on: "Wednesday")

let mappedNumbers = numbers.map({ number in 3 * number })

print(mappedNumbers)

类

class Square: NamedShape {
    var sideLength: Double

    init(sideLength: Double, name: String) {
        self.sideLength = sideLength
        super.init(name: name)
        numberOfSides = 4
    }

    func area() -> Double {
        return sideLength * sideLength
    }

    override func simpleDescription() -> String {
        return "A square with sides of length \(sideLength)."
    }
}
let test = Square(sideLength: 5.2, name: "my test square")
test.area()
test.simpleDescription()

class Square: NamedShape {

var sideLength: Double

init(sideLength: Double, name: String) {

self.sideLength = sideLength

super.init(name: name)

numberOfSides = 4

}

func area() -> Double {

return sideLength * sideLength

}

override func simpleDescription() -> String {

return "A square with sides of length \(sideLength)."

}

let test = Square(sideLength: 5.2, name: "my test square")

test.area()

test.simpleDescription()

枚举 | 结构体

enum Rank: Int {
    case ace = 1
    case two, three, four, five, six, seven, eight, nine, ten
    case jack, queen, king
    func simpleDescription() -> String {
        switch self {
        case .ace:
            return "ace"
        case .jack:
            return "jack"
        case .queen:
            return "queen"
        case .king:
            return "king"
        default:
            return String(self.rawValue)
        }
    }
}

struct Card {
    var rank: Rank
    var suit: Suit
    func simpleDescription() -> String {
        return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"
    }
}

enum Rank: Int {

case ace = 1

case two, three, four, five, six, seven, eight, nine, ten

case jack, queen, king

func simpleDescription() -> String {

switch self {

case .ace:

return "ace"

case .jack:

return "jack"

case .queen:

return "queen"

case .king:

return "king"

default:

return String(self.rawValue)

}

struct Card {

var rank: Rank

var suit: Suit

func simpleDescription() -> String {

return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"

}

错误处理

do {
    let printerResponse = try send(job: 1040, toPrinter: "Bi Sheng")
    print(printerResponse)
} catch {
    print(error)
}

let printerSuccess = try? send(job: 1884, toPrinter: "Mergenthaler")

do {

let printerResponse = try send(job: 1040, toPrinter: "Bi Sheng")

print(printerResponse)

} catch {

print(error)

}

let printerSuccess = try? send(job: 1884, toPrinter: "Mergenthaler")

泛型

func makeArray<Item>(repeating item: Item, numberOfTimes: Int) -> [Item] {
    var result = [Item]()
    for _ in 0..<numberOfTimes {
        result.append(item)
    }
    return result
}
makeArray(repeating: "knock", numberOfTimes: 4)

func makeArray<Item>(repeating item: Item, numberOfTimes: Int) -> [Item] {

var result = [Item]()

for _ in 0..<numberOfTimes {

result.append(item)

}

return result

}

makeArray(repeating: "knock", numberOfTimes: 4)