无法将 Int 类型的值转换为预期的参数类型“...”

Question

I was trying to understand how parameters work in Swift and thus wrote a simple class as follows

class NumberIncreaser {


func numberIncrementor(var number:Int)->Int{
    number += 1
    return number
}


var anotherNumber = numberIncrementor(3)



}

However even after explicitly mentioning that the method 'numberIncrementor' takes an Int , Xcode asks for a numberIncreaser object(hope I am using the correct terminology , new to programming) instead. I noticed that when I remove the class the method works perfectly fine. I would like to know why this is so and how can I resolve it.

Thanks!

Answer 1

Your code won't compile. Consider this:

class NumberIncreaser {

    static func numberIncrementor(var number:Int)->Int{
        number += 1
        return number
    }

}

var anotherNumber = NumberIncreaser.numberIncrementor(3)

Or one another variant:

class Number {

    var number: Int

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

    func increasedNumber() -> Int {
        return number + 1
    }
}

var anotherNumber = Number(number: 3).increasedNumber()

Answer 2

Also, don't use var in func parameter declarations:

class NumberIncreaser {
    static func numberIncrementor(number: Int) -> Int {
        let answer = number + 1
        return answer
    }
}

var anotherNumber = NumberIncreaser.numberIncrementor(3)

Answer 3

var parameters have been deprecated thus number is a constant which makes it immutable. You also cannot call numberIncrementor because it's an instance method.

A way out would be to make numberIncrementor a class or static method by prefixing the declaration with class or static keyword: class func numberIncrementor and you call it like so: NumberIncreaser.numberIncrementor(3) .

class NumberIncreaser {

  class func numberIncrementor(number: Int) -> Int {
    return number + 1
  }


  var anotherNumber = NumberIncreaser.numberIncrementor(3)

}

Another way would be to make anotherNumber a lazy property like so:

class NumberIncreaser {

  func numberIncrementor(number: Int) -> Int {
    return number + 1
  }


  lazy var anotherNumber: Int = self.numberIncrementor(3)

}