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iOS

Posted by alexr89
alexr89
4,045 Points

Extra Argument error with Super/Sub classes

I have been playing around in a Playground after completing a few videos on inheritance on the beginner iOS track. I used the example given at the end to create a vehicle superclass and then vehicle type sub classes. The code is as follows:

class Vehicle {
    var wheelCount: Int = 4
    var doorCount: Int = 4
    var license: String
    var topSpeed: Int = 150

    init(wheelCount: Int, doorCount: Int, license: String) {
        self.wheelCount = wheelCount
        self.doorCount = doorCount
        self.license = license
    }
}

class Bus: Vehicle {
    override init(wheelCount: Int, doorCount: Int, license: String) {
        super.init(wheelCount: wheelCount, doorCount: doorCount, license: license) {
            self.topSpeed = 55
        }
    }
}


let newCar = Vehicle.init(wheelCount: 4, doorCount: 4, license: "Standard")
let newBus = Bus.init(wheelCount: 6, doorCount: 2, license: "HGV")
newCar.topSpeed
newBus.topSpeed

However the code does not run with an error around the super.init in the "Bus" class, saying "error: extra argument 'license' in call super.init".

I have no idea at all why this is. I copied the example from the video (tower defence game) and just edited the values to match my vehicle example. Can anyone advise?

Thanks

2 Answers

Aniruddha Shukla
Aniruddha Shukla
2,846 Points

Those extra braces you added after you call super? Try removing them

class Vehicle {
    var wheelCount: Int = 4
    var doorCount: Int = 4
    var license: String
    var topSpeed: Int = 150

    init(wheelCount: Int, doorCount: Int, license: String) {
        self.wheelCount = wheelCount
        self.doorCount = doorCount
        self.license = license
    }
}
class Bus: Vehicle {

     override init(wheelCount: Int, doorCount: Int, license: String) {
        super.init(wheelCount: wheelCount, doorCount: doorCount, license: license)
        self.topSpeed = 55
    }
} 
let newCar = Vehicle.init(wheelCount: 4, doorCount: 4, license: "Standard")
let newBus = Bus.init(wheelCount: 6, doorCount: 2, license: "HGV")
newCar.topSpeed
newBus.topSpeed
alexr89
alexr89
4,045 Points
alexr89
alexr89
4,045 Points

That is correct! Thank you :!