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

Sam Belcher
Sam Belcher
3,719 Points

Generic Functions With Multiple Type Paremeters

I'm confused with why "append" isn't working and I am also not sure how to return a value of type "[U]"

func map<T, U>(array: [T], transformation: (T) -> U) -> [U] {
    var mapArray: [U] = []
    for number in array {
       return mapArray.append(transformation(number))

1 Answer

Magnus Hållberg
Magnus Hållberg
17,232 Points

Its not the append that is the problem, its where you are trying to return. You need to return the array after the new values are appended, now you are trying to appen each new value from the loop. Try to return the array after the loop.