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iOS Intermediate Swift 2 Extensions and Protocols Extending a Native Type

Not sure what they're asking me here. A little help?

Your task is to extend the String type and add a method that lets you add an integer value to the string. For example: "1".add(2) If the operation is possible, return an integer value. If the string does not contain an integer and you cannot add to it, return nil.

types.swift
// Enter your code below

extension String {
  var add: Int {
  if return {

  }
  else 
  { return nil }
  }

}

2 Answers

Tobias Helmrich
Tobias Helmrich
31,602 Points

Hey Manuel,

note that you have to extend the String type with an add method instead of a computed property.

One way you could implement this function is to use a guard statement where you try to change the string you're using the method on to an integer. If this doesn't work you can return nil, otherwise you can just add the passed number to the converted number and return the result.

Like so:

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

I hope that helps, good luck! :)

Hey, thank you Tobias! That was extremely helpful. It's a bit ironic how the world works. I was on your website this morning after you helped with a previous problem I had and now here you are helping me again. I appreciate your help!

Tobias Helmrich
Tobias Helmrich
31,602 Points

Haha, glad to hear that! I'm always happy to help! :)

Joshua Hudson
Joshua Hudson
5,237 Points

Thanks for the assist Tobias!

Sadly Im having to look up almost every one of Gabe's challenges as the videos will present something like "1 +1 = 2 and 2 + 2 = 4" and then the challenges read "Please calculate the mass of the sun". I'm finding it very difficult to learn from him as opposed to Pasan, whose challenges are a logical extension of the subject matter.

I made this complaint as well, the code challenges have little if anything to do with the videos.