Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS Generics in Swift Generics and Protocols Extending Generic Types

Sam Belcher
Sam Belcher
3,719 Points
Posted by 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
33,366 Points
Heidi Puk Hermann
Heidi Puk Hermann
33,366 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*/