Anyone with a device running iOS 7 (with AirDrop turned on) will show up in the AirDrop section of the Sharing sheet. To send a file, tap on the recipient's image and, after the recipient is alerted and accepts the transfer, the data is beamed over using Wi-Fi. For security, the point-to-point transfer is encrypted between the two devices.
AirDrop allows for easy file swaps between iOS 7 devices — when it works. It's still a bit flakey.
AirDrop settings are located in the Control Center, so turning it on/off and selecting whether to accept files from everyone or only people in your Contacts is easy. Also note: To use AirDrop, both Bluetooth and Wi-Fi must be on, although you don't actually need to be connected to a Wi-Fi network.
When it works, AirDrop works well. The recipient device avatars are supposed to show up automatically in the Sharing Sheets, but there were several times during testing that devices didn't show up until I toggled AirDrop on and off. Once the devices could "see" each other, AirDrop proved to be a fast and easy way to transfer files. It seems if you're relatively close to the other device — within about 15 feet — the transfer will begin reliably begin. Further away than that and you may have problems. Apple engineers need to improve the reliability, and make it possible to transfer files between Macs and iOS devices. The concept is already killer; it's the implementation that needs more polish.
Multitasking is greatly improved, as is the interface for switching between apps. Previously, when you pressed the home button twice, a small row of icons appeared at the bottom of the screen so you could quickly jump to recently-used apps. Depending on the direction of the swipe, you could also access other functions like music and brightness controls. In iOS 7, you still press the home button twice to switch between recent apps. But now the interface seems to zoom out to show you application previews above each app's icon. This makes it even easier to find what you're looking for.
Manually quitting an app is easier, too. You simply swipe up on the app when it appears in the multitasking bar. That's a lot better than having to double-tap Home, press and hold your finger on the app, and tap the X for the app.
Double-clicking the home button brings up the new multitasking view, showing which apps have been launched. To quit an app, just swipe up toward the top of the screen.
Background multitasking has been expanded, making iOS 7 the first version to allow full-on background processes for third-party apps that can take advantage of the new features. System apps that shipped with the device were always allowed more leeway than third-party apps, and Apple engineers had to craft APIs that allowed common functions to occur in the background.
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