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iOS Generics in Swift Generic Functions, Parameters and Constraints CSS Background Blend Modes Challenge

I wrote a piece of code and it works in the Xcode playground. But the Challenge question keeps complaining

func transform<T,U>(array arg: [T], transformation: (T) -> U) -> [U] { var array : [U] = [] for value in arg { array.append(transformation(value)) } return array }

//Test with this function func square(_ a: Int) -> Int { return a * a }

transform(array: [1,2,3,4], transformation: square)

generics.swift
func transform<T,U>(array arg: [T], transformation: (T) -> U) -> [U] {
    var array : [U] = []
    for value in arg {
        array.append(transformation(value))
    }
    return array
}

1 Answer

Jeff McDivitt
Jeff McDivitt
23,970 Points

You are very close, not sure why you are including "arg" as I believe that is throwing you off. Also you need to return the new array

func map<T, U>(array: [T], transformation: (T) -> U) -> [U] {
    var newArray = [U]()
    for values in array{
    newArray.append(transformation(values))
}

return newArray as! [U]

}
Jeff McDivitt
Jeff McDivitt
23,970 Points

And the function is called map not transform :)