Question

根据我的理解，方便初始化器是init缺少具有默认或硬编码值的属性，或者给予实现任何灵活数量的参数并满足 init规则，即所有属性都应该是在创建对象之前初始化。

像：

class A {

    var name:String;
    var salary:Float;

    init(name:String,salary:Float) {
        self.name = name;
        self.salary = salary;
    }

    convenience init(name:String) {
        self.init(name:name , salary:8000.0)
    }

}

但是我们也可以通过以下代码实现这一点并获得输出：

class A {

    var name:String;
    var salary:Float;

    init(name:String,salary:Float) {
        self.name = name;
        self.salary = salary;
    }

     init(name:String) {
        self.name = name;
        self.salary = 8000.0;
    }

    init() {
        self.name = "UnKnown name";
        self.salary = 0.0;
    }
}

let objectA = A(name: "murali")
print(objectA.name);
print(objectA.salary);

输出：

murali
8000.0

请说明我们将使用便利初始化器的哪些情况。

Answer 1

在简单的情况下，例如使用convenience init或手动设置属性没有太大区别。

在设置属性后，便捷初始化程序会派上用场，您必须执行一些复杂的逻辑并且不想复制代码。

此

class A {

    var name:String;
    var salary:Float;

    init(name:String,salary:Float) {
        self.name = name;
        self.salary = salary;

        //hundreds of line of very complicated logic in order to perform important stuff
    }

    convenience init(name:String) {
        self.init(name:name , salary:8000.0)
    }

}

比

更具可读性，更易于理解和管理未来的变更

class B {

    var name:String;
    var salary:Float;

    init(name:String,salary:Float) {
        self.name = name;
        self.salary = salary;

        //hundreds of lines of very complicated logic in order to perform important stuff
    }

    init(name:String) {
        self.name = name;
        self.salary = 8000.0;

        //the same, repeated, hundreds of lines as before of very complicated logic in order to perform the same important stuff
    }

}

我们为什么要方便初始化器而不是手动初始化器

1 个答案: