// Ensures the shake is strong enough on at least two axes before declaring it a shake. // "Strong enough" means "greater than a client-supplied threshold" in G's. static BOOL L0AccelerationIsShaking(UIAcceleration* last, UIAcceleration* current, double threshold) { double deltaX = fabs(last.x - current.x), deltaY = fabs(last.y - current.y), deltaZ = fabs(last.z - current.z); return (deltaX > threshold && deltaY > threshold) || (deltaX > threshold && deltaZ > threshold) || (deltaY > threshold && deltaZ > threshold); } @interface L0AppDelegate : NSObject { BOOL histeresisExcited; UIAcceleration* lastAcceleration; }