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 Intermediate Swift 2 Extensions and Protocols Extending a Native Type

Connor Crawford
Connor Crawford
6,405 Points

Keep getting an error saying "use of unresolved identifier NSNumberFormat()." Any other solution suggestions?

Xcode accepts my solution but workspaces does not. I would also like to try and find a solution that is more flexible than the one I came up with here. The goal is to add an integer to a string if the string contains an integer otherwise return nil. This have to be within an extension of the class String aka no stored properties. Thanks for the help!

types.swift
// Enter your code below
extension String {

    func add(int: Int) -> Int? {
        var myString: String = "1"

        if let myNumber = NSNumberFormatter().numberFromString(myString) {
            var myInt = myNumber.integerValue
            return myInt + int
        } else {
            return nil
        }

      }

}

1 Answer

Connor Crawford
Connor Crawford
6,405 Points

Figured out wayyyyy easier solution.

extension String { func add(intA: Int) -> Int? { if let intB = Int(self) { return intB + intA } else { return nil }

}

}