Swift_类和结构体

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struct Resolution {

    var width = 0

    var height = 0

}

class VideoMode {

    var resolution = Resolution()

    var interlaced = false

    var frameRate = 0.0

    var name: String?

}

///类和结构体

class ClassesStructures: NSObject {

    func test() {

        //      self.testClassStruct()                            // 类和结构体

        //      self.testStructuresAndEnumerationsAreValueTypes() // 结构体和枚举是值类型

        //      self.testClassesAreReferenceTypes()               // 类是引用类型

        //      self.testIdentityOperators()                      // 恒等算子

    }

    //类和结构体测试

    func testClassStruct() {

        //初始化

        let someResolution = Resolution()

        let someVideoMode = VideoMode()

        //访问属性

        print("someResolution.width：\(someResolution.width)")

        print("someVideoMode.resolution.width：\(someVideoMode.resolution.width)")

        someVideoMode.resolution.width = 1280

        print("someVideoMode.resolution.width：\(someVideoMode.resolution.width)")

        //通过成员初始化结构体

        let vga = Resolution(width: 640, height: 480)

        print(vga)

        /*  print

         someResolution.width：0

         someVideoMode.resolution.width：0

         someVideoMode.resolution.width：1280

         Resolution(width: 640, height: 480)

         */

    }

    //结构体和枚举是值类型

    func testStructuresAndEnumerationsAreValueTypes() {

        //结构体测试

        let hd = Resolution(width: 1920, height: 1080)

        var cinema = hd

        cinema.width = 2048 //改变cinema的值 不会改变hd中的值

        print("cinema.width：\(cinema.width)")

        print("hd.width：\(hd.width)")

        //枚举测试

        enum CompassPoint {

            case north, south, east, west

        }

        var currentDirection = CompassPoint.west

        let rememberedDirection = currentDirection

        //改变currentDirection rememberedDirection的值不会变化

        currentDirection = .east

        print("\(rememberedDirection)")

        /*  print

         cinema.width：2048

         hd.width：1920

         west

         */

    }

    //类是引用类型

    func testClassesAreReferenceTypes() {

        let tenEighty = VideoMode()

        tenEighty.frameRate = 25.0

        // 引用tenEighty到alsoTenEighty 并改变alsoTenEighty中的值

        let alsoTenEighty = tenEighty

        alsoTenEighty.frameRate = 30.0

        print("tenEighty.frameRate：\(tenEighty.frameRate)")

        /*  print

         tenEighty.frameRate：30.0

         */

    }

    //恒等算子

    func testIdentityOperators() {

        //恒等算子是===或!==

        let tenEighty = VideoMode()

        let alsoTenEighty = tenEighty

        if tenEighty === alsoTenEighty {

            print("相同实例")

        }

        /*  print

         相同实例

         */

    }

}