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iOS Generics in Swift Generics and Protocols Extending Generic Types

Sam Belcher
Sam Belcher
3,719 Points

Extending Generic Types

Hi, this lesson was really hard for me to understand and I don't know what to fix in my code, or if my logic is at all correct. 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 seems fine, but you are missing a closing curly bracket at the end... It is more clearly to see, if you indent the function.

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
   }
/*missing a closing bracket here*/