Thanks very much.
Re merging all the CSVs in a folder, I managed to get this to work some of the time. However, in certain situations (when testing a different subset of the CSVs), I encountered the following error (on a Xcode Playground).
"error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0). The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation."
If it is possible to see some example code (and receive guidance on the above error) to help, that would be much appreciated.
I also noticed the following warning:
'init(fileURLWithPath:)' will be deprecated in a future version of macOS. Use init(filePath:directoryHint:relativeTo:) instead.
As such, I used filePath rather than fileURLWithPath.
Thanks again.