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iOS Object-Oriented Swift Value vs Reference Types Final Challenge

Lei zheng
Lei zheng
7,990 Points
Posted by Lei zheng
Lei zheng
7,990 Points

Below you will find two classes that don't compile. Click on the preview button to see the errors. Look at the errors an

I can not get it right. especially how to set up default value in subclass. I need help here.

Vehicle.swift 
class Vehicle {
    let wheels: Int
    let doors: Int

    // Designated initializer
    init(wheels:Int, doors:Int){

    }
}

class Car: Vehicle {
    // A car must default to 4 wheels and 4 doors
    init(){
    self.wheels = 4
    self.doors = 4 
    super.init
      // call super.init
    }
}
Chokdee Srisuk
Chokdee Srisuk
19,384 Points

As base class, you have to initialize its own stored properties: wheels and doors by using self.wheels = wheels and self.doors = doors And then in subclass, you call designated initializer of superclass, give the value of 4 to wheels and doors with this sentence: super.init(wheels: 4, doors: 4).

Please check out the codes below.

class Vehicle { let wheels: Int let doors: Int

// Designated initializer
init(wheels:Int, doors:Int){
    self.wheels = wheels
    self.doors = doors
}

}

class Car: Vehicle { // A car must default to 4 wheels and 4 doors init(){ // call super.init super.init(wheels: 4, doors: 4) } }

Lei zheng
Lei zheng
7,990 Points
Lei zheng
Lei zheng
7,990 Points

thank you. so the super.init() should be under init(). that's the key. thank you.