Slight tweaks to Cortis Clark's joinedWithComma function

Array.joinedWithComma.swift

extension Array where Iterator.Element == String {
    /// Originally by Cortis Clark on StackOverflow, modified by Ben Leggiero for an example
    /// - SeeAlso: https://stackoverflow.com/a/52266604/3939277
    func joinedWithComma(useOxfordComma: Bool = true, maxItemCount: UInt8? = nil) -> String {
        let result: String
        if let maxItemCount = maxItemCount, count > maxItemCount {
            result = self[0 ..< maxItemCount].joined(separator: ", ") + ", etc."
        } else if count >= 2 {
            let lastIndex = count - 1
            let extraComma = (useOxfordComma && count > 2) ? "," : ""
            result = self[0 ..< lastIndex].joined(separator: ", ") + extraComma + " and " + self[lastIndex]
        } else if count == 1 {
            result = self[0]
        } else {
            result = ""
        }

        return result
    }
}



// Usage example:


let numbers = [1, 2, 3, 4]

print(numbers.joinedWithComma()) // Default; prints "1, 2, 3, and 4"
print(numbers.joinedWithComma(maxItemCount: 2)) // A maximum of 2 items; prints "1, 2, etc."
print(numbers.joinedWithComma(maxItemCount: 2)) // A maximum of 10 items; prints "1, 2, 3, and 4"
print(numbers.joinedWithComma(maxItemCount: nil)) // No maximum of items; prints "1, 2, 3, 4"
print(numbers.joinedWithComma(maxItemCount: -1)) // Unclear; fails to compile

Original answer by Cortis Clark on StackOverflow