Swift 学习笔记 5-对象和类

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对象和类

1.创建类: class + 类名
2.类中属性的声明和常量、变量一样，唯一的区别就是它们的上下文是类。方法的声明也一样。

class ClassTest{
    var varTest = 0
    func desc() -> String {
        return "ClassTest with varTest = (varTest)."
    }
}

var test = ClassTest();
test.varTest = 1;
print(test.desc())

输出:ClassTest with varTest = 1.

3.构造函数: init + 参数列表
4.self用来区别实例变量与参数

class ClassTest{
    var varTest = 0

    init(){
        varTest = -1;
    }

    init(varTest : Int){
        self.varTest = varTest
    }

    func desc() -> String {
        return "ClassTest with varTest = (varTest)."
    }
}

5.析构函数：deinit

class ClassA {
    var varStr = "sss";
}

class ClassTest{
    var varTest = 0
    var varA: ClassA? = ClassA()

    init(){
        varTest = -1;
    }

    init(varTest : Int){
        self.varTest = varTest
    }

    func desc() -> String {
        return "ClassTest with varTest = (varTest)."
    }

    deinit{
        varA = nil;
    }
}

6.继承: ：SuperClass
7.使用 super访问父类方法
8.使用 override覆盖父类方法

class ClassTrue: ClassTest {
    init(varTest :Int,varStr :String) {
        super.init(varTest: varTest)
    }

    override func desc() -> String {
        return "ClassTrue with varTest = (varTest)."
    }
}

9.属性: 使用闭包实现 get{ return XXX } set{ XXX = newValue }
10.属性中新值的名字是newValue

class ClassTest{
    var varTest = 0
    var varA: ClassA? = ClassA()

    var varGettersSetters: Int {
        get {
            return varTest
        }
        set {
            varTest = newValue
        }
    }

    init(){
        varTest = -1;
    }

    init(varTest : Int){
        self.varTest = varTest
    }

    func desc() -> String {
        return "ClassTest with varTest = (varTest)."
    }

    deinit{
        varA = nil;
    }
}


var test = ClassTest();
test.varTest = 1;
test.varGettersSetters = 100;
print(test.desc())

输出:ClassTest with varTest = 100.