Moving music between Mac and iPhone

The original iPod model was that

• You could sync an iPod to one Mac at a time
• Each synchronization replaced all of the music on the iPod with a fresh selection from the Mac's iTunes library.
• Synchronization was one-way, from Mac to iPod – never from iPod to Mac.
• You could not directly access the music on the iPod as if the iPod was an external drive. The iPod hid away the music files somewhere so that you could not mess with them - or use the iPod as a means to copy music from one computer to another.

A few possible reasons for this:

• Early iPods did not have a lot of computational power, and this design may have allowed the Mac to provide the iPod with a "crib sheet" for how to provide access to the particular music files loaded onto it.
• Assuming that you safeguarded your Mac's iTunes Library, this made it easy to load your music onto a new iPod.
• Making it impossible to use iPods to easily copy music from one computer to another may have helped to placate the recording industry, who fought home recording rights and equipment tooth and nail. (Remember: this is the same bunch who had to be dragged, kicking and screaming, by Steve Jobs and Apple, into realizing that people might actually pay for downloaded music if you just made it easy for them to buy it!)

That model, with modifications, was the basis for how iPhone/iPad/iPod synchronization works today. Set aside the cloud-based synchronization methods that require an iTunes Match or Apple Music subscription, and you can trace the manual synchronization design back to the very first iPod.

Music/Finder are designed to copy content from the local library to the device, not the other way around. I've not explicitly tested it lately, but for reasons unknown even a manually managed iPhone might have content removed from it if it wasn't also in the local library. Syncing to a new computer that doesn't already have your complete library copied to it can result in content being deleted from the device.

See Recover your iTunes library from your iPod or iOS device - Apple Community for advice on copying content from the device into your library.

tt2

ADH69 wrote:

When I do that, I get a warning it will erase all the existing music on the iPhone. I get a warning too if I try to manually sync the music.

As noted, see Recover your iTunes library from your iPod or iOS device - Apple Community for advice on copying content from the device into your library. Once everything is in your library, and ideally backed up for security, you can proceed with erasing the current content on the device and replacing it with the media in the library.

tt2

ADH69 wrote:

Thanks. I suspect the change in software has to do with Apple's subscription music service. It's hard to own things relating to computers now.

Things worked this way long before Apple offered any subscription music service.

Apple released the first iPod in October 2001. They launched iTunes Match in November 2011 – and Apple Music in June 2015.

ADH69 wrote:

When I do that, I get a warning it will erase all the existing music on the iPhone.

You can only synchronize against one computer at a time. So if you go to synchronize against a new computer, you're only allowed to do it by wiping the content loaded by the previous one.

Hi,

See Use the Finder to sync your iPhone, iPad or iPod touch with your Mac – Apple Support (UK)

Jim