Under the Bridge

Core Motion Slickness

The always-invaluable NSHipster has some particularly nifty trickiness in an article on Core Motion:

CMDevice​Motion

Let’s say we want to give the splash page of our app a fun effect, with the background image staying level no matter how the phone is tilted … Using the gyroscope, Core Motion separates user movement from gravitational acceleration and presents each as its own property of the CMDeviceMotionData instance that we receive in our handler…

We can also use the other, non-gravity portion of this composited gyro/acceleration data to add new methods of interaction. In this case, let’s use the userAcceleration property of CMDeviceMotionData to navigate backward whenever a user taps the left side of her device against her hand…

Lastly, let’s try using the device’s attitude to enable a new interaction for a flash-card app, designed to be used by two study buddies. Instead of manually switching between the prompt and the answer, we’ll automatically switch the view as the device turns around, so the quizzer sees the answer while the person being quizzed only sees the prompt…

Read it all!

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