Capturing serverModified into a variable in Swift

I'm new to Swift, and this is my first iOS application.  In fact, I'm fairly new to OO programming.  My background is mainframe z/OS.  So...

I needed to capture serverModified date in a field.  After much googling and trial and error, I finally made the code to parse it out of the MetaData.  It works, but is there a slicker way to do this? 

Thanks!

Here is the code I used to do it:

let dispatchGroup = DispatchGroup()
.
.
.

        
        // Check to see if Nvelopes.csv exists in Dropbox and get the servermodified date.

        dispatchGroup.enter()
        client!.files.getMetadata(path: "/Nvelopes.csv")
            .response {response, error in
                if let (metadataNvelopes) = response
                {
                    let nsstringMetadataNvelopes = NSString(string: metadataNvelopes.description)
                    var serverModifiedSeparator = "\"server_modified\" = \""
                    let serverModifiedArray = nsstringMetadataNvelopes.components(separatedBy: serverModifiedSeparator)
                    
                    if serverModifiedArray.count > 0 {
                        print("serverModifiedArray begin")
                        print(serverModifiedArray[0])
                        print(serverModifiedArray[1])
                        print("serverModifiedArray end")
                        serverModifiedSeparator = "\";"
                        let ServerModifiedArray = serverModifiedArray[1].components(separatedBy: serverModifiedSeparator)
                        let serverModified = ServerModifiedArray[0]
                        print("serverModified:" , serverModified)
                        
                    }

                    dispatchGroup.leave()

                } else if let error = error {
                    print("Did not find Nvelopes.csv in Dropbox:")
                    print(error.description)
                    dispatchGroup.leave()
                }