Xcode Swift 3.0 macOS (Sierra) app cannot create file, without permission

I am new to Xcode and Swift. I am trying to create a file called "file.txt" in my Documents folder and get the error "You do not have permission to save the file."

Ultimately, I do NOT want to use the default Docs directory as I am using FIFinderSyncController to view everything ("/").

    let targetFile = (FIFinderSyncController.default().targetedURL()?.path)! + "/file.txt"

    NSLog("%@", targetFile as NSString)

    let fileManager = FileManager.default
    if fileManager.fileExists( atPath: (targetFile) ) == false {

        do {
            let targetString = (FIFinderSyncController.default().targetedURL()?.path)! + "/Untitled.txt"

            NSLog("%@", targetString as NSString)

            let fileManager = FileManager.default

            if fileManager.fileExists( atPath: targetString ) == false {
                let content = "" // Just creating empty file.

                //writing
                try content.write(toFile: targetString, atomically: false, encoding: String.Encoding.utf8)

                //reading
                let readingText = try NSString(contentsOfFile: targetString, encoding: String.Encoding.utf8.rawValue)

                NSLog("%@", readingText as NSString)
            }
        }
        catch {
            print(error.localizedDescription)
        }
    }

      

        
        
        
      

    

The log shows:

2017-04-06 13:35:46.450077-0700 Open New Text File[5177:1035580]     /Users/david/Documents/file.txt
2017-04-06 13:35:46.450257-0700 Open New Text File[5177:1035580]     /Users/david/Documents/file.txt
You don’t have permission to save the file "file.txt" in the folder "Documents".