Syncing goes from computer to device. Before you connect your iphone you need to disable auto syncing: Edit>Preferences>Devices: Prevent...from syncing automatically.
First copy the entire iTunes folder from your old computer to your new one using one of the methods outlined here: http://support.apple.com/kb/HT4527. Then you will also need to copy any other content you may have been syncing that is not part of your iTunes library, such as your contacts, calendar and any photos synced from your computer to your phone. Once that is all in place you should be able to sync with your new computer without issues.
Did I tell the OP to restore from a backup? No, I said to create a backup on the new computer that way if data is ever lost a backup is there.
You can't "sync" all the information from an iphone to a computer. You can move libraries, transfer purchases, create back ups, etc. but you can't really move all the data from the iphone to the computer.
If the OP doesn't disable auto sync and connects to the new computer then the data on the iphone could be replaced.
So if syncing is as you say unidirectional, if you lost your laptop or it was stolen you're screwed because you're now stuck with an ophaned iPhone. Surely the system can't be that obtuse.
There must be some reasonable way to sync your iPhone with a new replacement laptop without fear of having all your data overwritten.
A little digging turned up these:
So it depends on where your iPhone content came from. If your music, apps, etc are all from Apple then you're golden. If not Apple is raising its sizable middle finger at you and everyone else in that same boat.
There are many utilities to accessing your iPhone's file directly like "DiskAid" and "iExplorer" -- they don't provide a perfect solution, but at least you'll be able to rescue your files. And with your regained sanity you can start re-evaluating your choice to use Apple products and services.
I have also question ... I have to repair my Computer and reinstall Windows, so I have to install iTunes again, but I don't know if I will loose all my data, phone numbers and etc. from my iphone when I connected it with my reinstalled PC ... so please help me... I am still not that good with iphones and itunes
You actualy can copy your contents (apps i suppose) to your new computer.
Install the latest version of Itunes on your computer, (do not connect the iphone yet) Dissable sync in Itunes
Now just authorize this computer in the Itunes Store Tab ( you can add 5 different computer to Itunes)
Now you can copy your app's by going to File: Transfer purchases from "...." (do this every time if you use your phone on different computers)
This will copy your Legal purchases to the new computer.
Now click on the Sync Apps in Itunes "Devices" on the Apps Tab
(it will not automaticly start the sync).
You can do that after your accreed with the format.
If i'm wrong please replay, It worked on mine!
These are two possible approaches that will normally work to move an existing library to a new computer.
- Backup the library with this User Tip.
- Deauthorize the old computer if you no longer want to access protected content on it.
- Restore the backup to your new computer using the same tool used to back it up.
- Keep your backup up-to-date in future.
Connect the two computers to the same network. Share your <User's Music> folder from the old computer and copy the entire iTunes library folder into the <User's Music> folder on the new one. Again, deauthorize the old computer if no longer required.
Both methods should give the new computer a working clone of the library that was on the old one. As far as iTunes is concerned this is still the "home" library for your devices so you shouldn't have any issues with iTunes wanting to erase and reload.
I'd recommend method 1 since it establishes an ongoing backup for your library.
If you have an iOS device that syncs with contact & calendar data on your computer you should migrate this information too. If that isn't possible create a dummy entry of each type in your new profile and iTunes should offer to merge the existing data from the device into the computer, otherwise the danger is that it will wipe the information from the device.
If your media folder has been split out from the main iTunes folder you may need to do some preparatory work to make it easier to move. See make a split library portable.
Should you be in the unfortunate position where you are no longer able to access your original library, or a backup of it, then see Recover your iTunes library from your iPod or iOS device for advice on how to set up your devices with a new library with the maximum preservation of data.