For a long time I struggled around the possibility of synchronizing any given iDevice, be it an iPhone, iPad or iPod Touch, in more than one computer. There were uncountable times that I received a client’s device to troubleshoot (for example, to see why he wasn’t being able to successfully install an AdHoc build), and when I tried to synchronize it with my iTunes, there would be a message saying that all applications would be deleted. Heck, that’s not why I wanted to do.
Maybe I was looking at the wrong place or doing the wrong searches on Google, but it took me some time to figure out the correct approach to handle this problem. There are two possible situations you may face, which are:
1) Synchronize your own device in more than one computer
This is the simplest of the cases: you have an iPhone, iPad or iPod Touch, and want to sync it at your home’s computer and at your company’s computer. Please bear in mind that you are allowed to do such thing up to 5 computers. Connect your device via an usb cable and fire up iTunes, then go to the Store menu and choose Authorize This Computer. Enter your credentials, and after that go to the File menu and choose Transfer purchases from ….. Wait until it finishes, and you are good to go.
2) Synchronize more than one device in the same computer
This is a bit more elaborated, and handles the situation where you have multiple devices that you need to sync in the same computer – note that it’s a different need than the previous, where it states out to sync the device in different computers. The question here is how not to mess with your own library when someone else’s device is sync’d at your iTunes.
To correctly perform this task, you will need to think about multiple iTunes libraries (or multiple accounts), and then perform the steps previously described at (1). Do the following:
Quit iTunes, and before opening it again, hold down the Option key (Mac) or Shit key (Windows), and without releasing it, fire up iTunes. A dialog window saying that you should “Choose iTunes Library” will open, as shown in the image below:
Select “Create Library” and place it wherever you want. That would be the location where the files will be stored, so if you want to use it other than for temporary purposes, please make sure you choose a good directory.
One you do that, do the steps at (1). To switch between libraries, to the same Option or Shift trick again, but then select “Choose Library” instead.