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iOS Generics in Swift Generics and Protocols Extending Generic Types

Sam Belcher
Sam Belcher
3,719 Points

Extending Generic Types

I'm stuck. Not sure if my logic is correct, and overall this lesson was pretty difficult for me. Thanks!

generics.swift
protocol PrefixContaining {
  func hasPrefix(_ prefix: String) -> Bool
}

extension String: PrefixContaining {}

// Enter code below
extension Array where Element: PrefixContaining {

func filter(byPrefix prefix: String) -> [Element] {
    var newArray: [Element] = []

    for item in self {
        if item.hasPrefix(prefix) {
            newArray.append(item)
        }
    }

    return newArray
}

1 Answer

Heidi Puk Hermann
Heidi Puk Hermann
33,351 Points

Hi,

your logic is spot on, but you are missing a closing curly bracket } at the end. If you indent your code, it is more clearly :)

extension Array where Element: PrefixContaining {

   func filter(byPrefix prefix: String) -> [Element] {
       var newArray: [Element] = []

       for item in self {
           if item.hasPrefix(prefix) {
               newArray.append(item)
           }
       }

       return newArray
   }

/* your are missing a curly bracket here :)*/