Unlike days gone by, you no longer have to connect your device to your Mac or PC when you want to sync your information or download a subsequent software update. There are two features at work here: iTunes Wi-Fi Sync and Software Update.
Wi-Fi Sync (as its name suggests) allows your iPhone 4S to sync with your computer over a Wi-Fi network rather than through a USB connection. It’s slightly slower, but you can do it any time your phone is on the same Wi-Fi network as your desktop computer. Better still, your device stays perpetually connected: You can adjust settings and re-sync without having to disconnect and reconnect any cables. (You can always continue to sync the old-fashioned way, of course.) Another benefit to this perpetual connection is that when syncing, you’re not stuck with a Do Not Disconnect screen while updating your song list or changing a setting; instead, it all happens in the background, allowing you to multitask and use your phone during a sync session.
Set Up Wi-Fi Sync
To enable Wi-Fi Sync, you need to connect your phone to your computer and open up iTunes. Click on your device in the Source list and then scroll down to the bottom of the summary pane.
Your device syncs with your computer only when iTunes is running; because of this, you need to check the first two boxes in the Options section: Open iTunes When This Phone Is Connected, and Sync With This iPhone Over Wi-Fi. Press the Sync button to save your changes, and you’re all set. By default, your device will automatically sync with iTunes any time it’s plugged into a power source and both are on the same Wi-Fi network; you can also force a sync by going to the Settings app on your device and tapping General -> iTunes Wi-Fi Sync and then tapping Sync Now.
Install iOS Updates If you’ve ever used an iOS device before, you may be familiar with the process of downloading app updates from the App Store app: When a little red badge appears in the upper right corner of the App Store icon, you open the App Store, navigate to the Updates tab, and download your app updates all at once, or one by one. The Software Update process is remarkably similar; but instead of going to the App Store, you go to the Settings app for any system updates.
Like the App Store, your device perpetually checks for new software updates in the background. When one is available, you’ll see a red badge appear on the Settings app; to download it, open the app and navigate to General -> Software Update. There, you can read some brief information about the update and install it by tapping a button. You can also force the system to check for an update by navigating to the Software Update pane.
Because these iOS updates are “delta updates” (they contain only the parts of the system that have changed, so you don’t have to download the entire system each time there is an update), they’re smaller; therefore, you can download them just about anywhere you have a decent 3G or Wi-Fi connection—on the bus, at home, walking down the street, you name it. To install these updates, however, you need to have at least 50 percent battery life on your device, or have it plugged into a power source.
Just as a friendly reminder: Even though you can install these updates anywhere, you should always (always, always) back up your device before you do. You can use Wi-Fi Sync to back up to your computer, or, if you have iCloud Backup enabled, you can use that.