IPhone – How to sync a particular music folder to iPhone

No, iTunes will not "listen" for music in a given folder (like the popular BT program Transmission, which will load torrent files once they've been downloaded to a given directory).

You have to manually add music by dragging it in the iTunes window or going through the file menu (CMD + O).

However, you could achieve what you are after perhaps with some voodoo in Apple Script. Or simply sort the contents of your music folder by "date added" (provided you are using Lion) and manually add the songs as they arrive.

But then if you are going through all this trouble of manually managing files, you may wish to ask yourself, "why"? It might be less of a burden to just let iTunes do its thing (like it was mentioned before, you can tell iTunes to copy the music anywhere you like, on any drive connected to your system, even on a network) than micro-manage a bunch of files.

By design, the iPhone will sync iTunes content with one computer at a time. Any attempt to sync such content with a second computer will result in ALL iTunes content being first erased from your phone & then replaced with the content from the second computer. This is a design feature and cannot be overridden. Because you replaced your computer, or hard drive, your phone will see this as a "new" computer. The iTunes content sync is one way: computer to phone. If you have photos that were synced to your phone or music ripped on your own that were not backed up, you will first have to extract them from your phone using third party software such as Touch Copy, before you do anything else, as Apple makes no provision to do so. Try this

Past iTunes, App store, & iBookstore content can be re-downloaded. Read here:

http://support.apple.com/kb/HT2519

Once you've done that, do the following in the order specified:

1. Disable auto sync when an iPod/iPhone is connected under iTunes>Preferences>Devices(under Edit menu if using Windows).

2. Make sure you have one contact & one event in the supported applications on your computer(iCal & Address Book on a Mac, Windows Address Book or Outlook if using Windows). These entries can be fake, doesn't matter, the important point is that these programs not be empty.

3. Connect your phone, iTunes running, do not sync at this point.

4. Store>Authorize this computer.

5. File>Transfer Purchases(To make sure all purchased content on your phone will be in your iTunes library).

6. Right click your phone in the left device pane & select "Reset warnings".

7. Right click again and select "Backup".

8. Right click again & select "Restore from Backup", select the backup you just made. When prompted to create another backup, decline.

9. This MUST be followed by a sync to restore your iTunes content, which you select from the various tabs, You'll get a popup regarding your contacts & calendars asking to merge or replace, select "Merge".

Your phone should look just like it did when you started, with no data loss.

You should be good to go.