Swift：在init中调用self方法

Question

I want to implement something like this:

class A {
    var a, b, c, d: Int

    init() {
        reset()
    }

    func reset() {
        a = 1
        b = 2
        c = 3
        d = 4
    }

    func blablabla() { 
        ...
    }
}

which cannot get compiled, error message:

Variable "self.a" used before being initialized

It doesn't make sense that I will have to copy the code from reset() into init() .

Is it a defect or is there another way to do it?

Answer 1

No, it's not a defect, simply self cannot be referenced in an initializer until all stored properties have been initialized, and a super class initializer has been invoked (if any).

In your case it seems legit to do the initializations in a method, and call that from the initializer, but unfortunately it doesn't work.

Possible solutions:

• make the properties optional or implicitly unwrapped (discouraged, unless you really need them optionals)

• initialize the properties with fake values before calling reset :

   init() { self.a = 0 self.b = 0 self.c = 0 self.d = 0 reset() } 

  or

   var a = 0 var b = 0 var c = 0 var d = 0 init() { reset() } 

Answer 2

提供a，b，c和d默认值，尤其是如果您要立即更改它们时。