触摸校准转速

Question

I'm rotating a view using the following way:

override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {
        for touch in touches{
        rotatableView.transform = CGAffineTransformMakeRotation(degreesToRadian(i++))
        }
    }

By anyway can I calibrate this rotation with the speed of moved touches?

Answer 1

As i understood , you want your UIImageView to rotate as fast as your finger , in other words , you mean that , "how fast my finger moves , is how fast the rotation is " .

in that sense , here is the code

override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {
    let t = touches.anyObject() as UITouch
    let position = t.locationInView(self.view)

    let target = rotatableView.center        
    let angle = atan2(target.y-position.y , target.x-position.x)
    rotatableView.transform = CGAffineTransformMakeRotation(angle)

}

atan2 is a mathmatical function , you can read more about it here