I am using the accelerometer to scroll multiple subViews in a UIScrollVIew. I want the view (portrait orientation) to scroll to the right when the user flicks the iPhone to the right, and scroll to the left when the device is flicked to the left.
I thought I could do that just by noting positive or negative x acceleration values, but I see that the values are usually a mixture of positive and negative values. I have set the floor at 1.5g to eliminate non-shake movement, and am looking at the x values over the duration of .5 seconds.
I'm sure there is a trigonometrical method for determining the overall direction of a flick, and that you have to measure values over the duration of the flick motion. I'm also sure that someone has already figured this one out.
Any ideas out there?
Thanks
I developed a solution which gives me better feedback than the proposed solution (only for left and right shake). The way I did it here is quite sensitive (recognizes a small shake), but sensitivity can be adapted by changing tresholdFirstMove and tresholdBackMove (increase for lower sensitivity)
In Swift : (in your viewController. And add "import CoreMotion")
var startedLeftTilt = false
var startedRightTilt = false
var dateLastShake = NSDate(timeIntervalSinceNow: -2)
var dateStartedTilt = NSDate(timeIntervalSinceNow: -2)
var motionManager = CMMotionManager()
let tresholdFirstMove = 3.0
let tresholdBackMove = 0.5
override func viewDidLoad() {
// your code
motionManager.gyroUpdateInterval = 0.01
}
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
motionManager.startGyroUpdatesToQueue(NSOperationQueue.currentQueue(), withHandler: { (gyroData, error) -> Void in
self.handleGyroData(gyroData.rotationRate)
})
}
private func handleGyroData(rotation: CMRotationRate) {
if fabs(rotation.z) > tresholdFirstMove && fabs(dateLastShake.timeIntervalSinceNow) > 0.3
{
if !startedRightTilt && !startedLeftTilt
{
dateStartedTilt = NSDate()
if (rotation.z > 0)
{
startedLeftTilt = true
startedRightTilt = false
}
else
{
startedRightTilt = true
startedLeftTilt = false
}
}
}
if fabs(dateStartedTilt.timeIntervalSinceNow) >= 0.3
{
startedRightTilt = false
startedLeftTilt = false
}
else
{
if (fabs(rotation.z) > tresholdBackMove)
{
if startedLeftTilt && rotation.z < 0
{
dateLastShake = NSDate()
startedRightTilt = false
startedLeftTilt = false
println("\\\n Shaked left\n/")
}
else if startedRightTilt && rotation.z > 0
{
dateLastShake = NSDate()
startedRightTilt = false
startedLeftTilt = false
println("\\\n Shaked right\n/")
}
}
}
}
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