Extract data from Algorithmia response

I am currently making an app that sends data to an Algorithmia algorithm where it is processed. A response of where to find the file is then sent back to the app in this form:

Optional({
output = "data://.algo/deeplearning/AlgorithmName/temp/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.png";})

I need a way to extract the randomly generated 'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.png' section of the response. It needs to be stored in a string which I will use later.

• Programming language: Swift 3
• Device: iOS
• Library in use: Algorithmia (https://algorithmia.com) (https://github.com/algorithmiaio/algorithmia-swift)

Final code:

if let json = response as? [String: Any] {
                print(json)

                let filePath = json["output"] as? String
                print("File path: \(filePath!)")

                let uwFilePath = filePath!

                let index = uwFilePath.index(uwFilePath.startIndex, offsetBy: 57)
                self.imageFileName = uwFilePath.substring(from: index)

                print(self.imageFileName)
            }

imageFileName is storing the final file name for later use. The begining part of the output string is also being cut off.