Mutable pathExtension on URLComponents

URLComponents+PathExtension.swift

// Swift 3

extension URLComponents {
    var pathExtension: String {
        get {
            return NSString(string: self.path).pathExtension
        }
        set {
            let nsStringPath = NSString(string: self.path)
            let nsStringPathWithoutExtension = NSString(string: nsStringPath.deletingPathExtension)
            if let nsStringWithNewExtension = nsStringPathWithoutExtension.appendingPathExtension(newValue) {
                self.path = nsStringWithNewExtension
            }
        }
    }
}