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iOS Intermediate Swift Extensions and Protocols Extending a Native Type

Jesse Gay
Jesse Gay
Full Stack JavaScript Techdegree Student 14,045 Points

Extending String with add func works in Xcode, but fails challenge. Why?

My solution works in Xcode but fails the challenge. Does anyone know why? The hint says "Make sure you're adding an add method that takes an Int and returns Int?" but I think my solution meets those criteria. The "best answer" for this challenge was similar, but used a guard statement instead. Thanks!

// Enter your code below
extension String {
    func add(_ value: Int) -> Int? {
        if let convertedNumber = Int(self) {
            return (value + convertedNumber)
        } else {
            return nil

2 Answers

Magnus Hållberg
Magnus Hållberg
17,232 Points

Its just a small thing, you are omitting the external name in your method. The challenge doesn't tell you to do that so that gives you an error even though there is nothing wrong with your code. /M