Swift find all occurrences of a substring

Question

I have an extension here of the String class in Swift that returns the index of the first letter of a given substring.

Can anybody please help me make it so it will

Answer 1

You just keep advancing the search range until you can't find any more instances of the substring:

extension String {
    func indicesOf(string: String) -> [Int] {
        var indices = [Int]()
        var searchStartIndex = self.startIndex

        while searchStartIndex < self.endIndex,
            let range = self.range(of: string, range: searchStartIndex..