iOS update question

[budman1187]

I've had my iPhone 3GS on the firmware 3.1.2 since I bought. The reason is, I've been scared to update it as I've heard you have to restore it to the factory default to do this. In other words, you lose everything except the appstore apps. So this is my question:

-If I want to update from 3.1.2 to iOS 4.2.1, what would be the easiest way to do it? Backup, restore to factory default, update iOS, jailbreak then sync with my backup? Or is there an easier way?

-And secondly, if I do this do I lose all my cydia apps, settings and configurations? Or is there a way to save all that?

Help appreciated

[i.Annie]

Firstly, if it's an new boot 3GS, the jailbreak will be tethered. The jailbreak for 4.2.1 is only for those who don't need unlocking (unless the new unlock comes out tomorrow or soon-ish). The old boot 3GS will not experience the tethered jb. So be aware of that.

Secondly, if you rely on an unlock, wait for the unlock.

Thirdly, to back things up such as contacts and apps, sync the device to iTunes. Be sure for contacts to go to the info tab in iTunes to enable the sync for contacts. Right-click device and select "transfer purchases" to ensure you sync apps you have on your phone that isn't in iTunes such as purchases through the app store.

For jailbreak apps from Cydia, use aptbackup or Pkgbackup. I recommend Pkgbackup because you don't have to restore from back up to use it. You'll want to set your phone up as new and avoid restoring from back up is why. Pkgbackup will save the Cydia stuff as a contact so if you install it, back up your stuff and sync to iTunes with contacts, you'll be able to regain them after the restore. To regain them, simply after restoring install Pkgbackup again and sync to iTunes.

Edit: as for photos, be sure to back them up manually to your comp. You'll likely lose those since you won't be restoring from back up. So save photos and videos manually as they are the only things iTunes won't back up unless you restore from back up, which like I said should be avoided as it could carry over previous jb items and could potentially cause conflict with a new jailbreak on the newly restore phone.

[budman1187]

Yea it's a newboot 3GS, so having a tethered JB isn't a problem as I'm used to us. And no, I don't rely on an unlock.

So if I'm reading all this right, and if I use pkgbackup, I should have no problems in regaining all my data after the 4.2.1 update?

[i.Annie]

Yes, as long as you sync your contacts and can sync them back into the phone, you can use Pkgbackup to regain all your Cydia stuff. I do have to warn you that you should remove anything that isn't compatible with iOS 4. some apps that are functional on 3.1.x won't work on iOS 4 and can cause your device to crash into safe mode. You should check the descriptions in Cydia for apps or tweaks. They usually say they are 4.x compatible, if they aren't remove them before using Pkgbackup.