Handoff can be used for a number of different activities, including email, web browsing, messaging, and more. Users can begin composing an email on their iPhone and finish it on their Mac. Maps and websites work in a similar fashion, as users can load up content on one device and look at it on another. Currently, Handoff works with Mail, Safari, Pages, Numbers, Keynote, Maps, Messages, Reminders, Calendar, and Contacts. A number of third-party apps including Pixelmator, Wunderlist, PCalc, and Things also contain support for Handoff.
You will need iOS 8.1 and OS X Yosemite in order to use Handoff. You also need to make sure that both your Mac and iPhone are logged into the same iCloud account, and check that your Mac supports Handoff. You can check if your Mac is compatible with Handoff by clicking the symbol in the top left-hand side of the Menu bar, going to About This Mac, clicking on System Report and clicking on the "Bluetooth" section. You should then see information about whether your system is compatible with Handoff.
Handoff is compatible with a select number of devices running iOS 8, including the iPhone 5 and later, the iPad Air, the iPad Air 2, the iPad 4, all models of the iPad mini, and the fifth-generation iPod Touch.
Handoff is limited to Macs with Bluetooth 4.0, which leaves many older Macs unable to access the new features. Additionally, even though the 2011 MacBook Air and 2011 Mac mini include Bluetooth 4.0, Apple has chosen to make both devices incompatible with OS X Yosemite's Continuity features. To solve this issue, a number of talented members of the MacRumors forums have come up with a set of instructions and a Continuity Activation Tool that should get Continuity working on Macs unable to support the feature.
Setting Up Handoff
1. Turn on Wi-Fi on your iPhone (Settings -> Wi-Fi) and Mac (Menu Bar -> Wi-Fi -> Turn Wi-Fi On.
2. Turn on Bluetooth on your iPhone (Settings -> Bluetooth) and Mac (Menu Bar -> Apple -> System Preferences -> Bluetooth -> Turn Bluetooth On).
3. Turn on Handoff on your iPhone (Settings -> General -> Handoff & Suggested Apps -> Turn Handoff On) and Mac (Menu Bar -> Apple -> System Preferences -> General -> Recent Items - > Turn On "Allow Handoff Between this Mac and your iCloud devices")
4. You may now begin using Handoff by launching a compatible app on your Mac or iOS device and swapping to another to see your content. For example, try launching Safari on your Mac and then switch to your iPhone. On your iPhone's lock screen, you should see a small Safari icon in the lower left corner. Slide up to launch Safari, and the iOS app will display the same website as seen on your Mac.
You can also see a Handoff-enabled app through the multitasking switcher by double-pressing your home button and scrolling to the left.
Handoff works in a similar fashion when transitioning from an iOS device to a Mac. On the Mac, a Handoff-compatible app will be displayed on the left-most side of the dock. Clicking on the app in the Mac's dock will load the same content as seen on an iOS device.
Since the launch of OS X Yosemite and iOS 8 earlier this month, many users have had issues getting Handoff to work with their devices.
Users on our forums seem to have found that the most common solution is a combination of logging out and back into iCloud on their devices, disabling and enabling Handoff, disabling and enabling Bluetooth, and restarting devices. But even amongst those who found success, it may not last forever. Handoff clearly remains buggy in this early release.
If those steps don't work for you, members on Apple's own support forums have also suggested that deleting Bluetooth preferences in OS X and then restarting Bluetooth can also solve problems with Handoff, but we haven't been able to get that to work on our end.
Any of these steps may help if you are having trouble with activating Handoff on your devices, but ultimately, Apple may have to release an update to allow Handoff to work consistently for everyone.