如何使用swift类方法

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类的实例方法

//类的实例方法class Counter {    var count = 0        func increment() {        count += 1    }        func increment(by count: Int) {        self.count += count    }        func reset() {        count = 0    }}let counter = Counter()print(counter.count)//0counter.increment()print(counter.count)//1counter.increment(by: 10)print(counter.count)//11counter.reset()print(counter.count)//0

结构体修改属性 mutating

//结构体修改属性 mutatingstruct Point {    var x = 0.0, y = 0.0    mutating func moveBy(x deltaX: Double, y deltaY: Double) {        x += deltaX        y += deltaY    }}var point = Point(x: 1.0, y: 1.0)point.moveBy(x: 2.0, y: 2.0)print(point)//Point(x: 3.0, y: 3.0)

枚举修改属性 mutating

//枚举修改属性 mutatingenum TriStateSwitch {    case off, low, high    mutating func next() {        switch self {        case .off:            self = .low        case .low:            self = .high        case .high:            self = .off        }    }}var ovenLight = TriStateSwitch.lowprint(ovenLight)//lowovenLight.next()print(ovenLight)//highovenLight.next()print(ovenLight)//off

类方法

//类方法class Tool {    static func getSize() -> (Int, Int) {        return (100, 100)    }}print(Tool.getSize())//(100, 100)

结构体用下标访问 subscript

//结构体用下标访问 subscriptstruct TimesTable {    let multiplier: Int    subscript(index: Int) -> Int {        return multiplier * index    }}let threeTimesTable = TimesTable(multiplier: 3)print(threeTimesTable[4])//12

类用下标访问 subscript

//类用下标访问 subscriptclass Matrix {    let rows: Int, cols: Int        var grid: [Double]        init(rows: Int, cols: Int) {        self.rows = rows        self.cols = cols        grid = Array(repeating: 0.0, count: rows * cols)    }        func indexIsValid(row: Int, col: Int) -> Bool {        return row >= 0 && row < rows && col >= 0 && col < cols    }        subscript(row: Int, col: Int) -> Double {        get {            assert(indexIsValid(row: row, col: col), "Index out of range")            return grid[(row * cols) + col]        }                set {            assert(indexIsValid(row: row, col: col), "Index out of range")            grid[(row * cols) + col] = newValue        }    }}var matrix = Matrix(rows: 2, cols: 2)print(matrix.grid)//[0.0, 0.0, 0.0, 0.0]matrix[0, 0] = 1.0matrix[0, 1] = 2.0matrix[1, 0] = 3.0matrix[1, 1] = 4.0print(matrix.grid)//[1.0, 2.0, 3.0, 4.0]

枚举用下标访问 subscript

//枚举用下标访问 subscriptenum Direction: Int {    case top, right, bottom, left    static subscript(n: Int) -> Direction {        return Direction(rawValue: n)!    }}let right = Direction[1]print(right)//right

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