Rotating UIView (Again) - ios

Question

I'm encountering some problems with rotating a uiview again. This time, im trying to rotate a uiview 1/12 the speed of another uiview I'm rotating at normal speed. However, when I try to accomplish this task, the uiview I'm trying to move slower moves like this:
1st Update
https://www.youtube.com/watch?v=wj3nRJo5CMM&feature=youtu.be
2nd Update
https://www.youtube.com/watch?v=YLRkUzXSDtQ&feature=youtu.be
Here's my code:
- (void)rotateHand:(UIPanGestureRecognizer *)panGesture {
if ([(UIPanGestureRecognizer*)panGesture state] == UIGestureRecognizerStateBegan) {
CGPoint touchPoint = [panGesture locationInView:[self view]];
float dx = touchPoint.x - minHandContainer.center.x;
float dy = touchPoint.y - minHandContainer.center.y;
arcTanMin = atan2(dy,dx);
arcTanHour = atan2(hourHand.center.x - minHandContainer.center.x, hourHand.center.y - minHandContainer.center.y);
if (arcTanMin < 0) {
arcTanMin = 2 * M_PI + arcTanMin;
}
if (arcTanHour < 0) {
arcTanHour = 2 * M_PI + arcTanMin;
}
NSLog(#"arcTanMin %f", arcTanMin);
startTransformMin = minHandContainer.transform;
startTransformHour = hourHandContainer.transform;
}
if ([(UIPanGestureRecognizer*)panGesture state] == UIGestureRecognizerStateChanged) {
CGPoint pt = [panGesture locationInView:[self view]];
float dx = pt.x - minHandContainer.center.x;
float dy = pt.y - minHandContainer.center.y;
float ang = atan2(dy,dx);
if (ang < 0) {
ang = 2 * M_PI + ang;
}
float angleDifferenceM = arcTanMin - ang;
float angleDifferenceH = arcTanHour + angleDifferenceM * (1.0/12.0);
NSLog(#"angleDiffM %f", angleDifferenceM);
NSLog(#"angleDiffH %f", angleDifferenceH);
minHandContainer.transform = CGAffineTransformRotate(startTransformMin, -angleDifferenceM);
hourHandContainer.transform = CGAffineTransformRotate(startTransformHour, -angleDifferenceH);
}
}

Answer 1

It appears that you're using arcTanMin as the starting reference angle for both the minute hand and hour hand. So when you make the jump across the x-axis, both angleDifferenceM and angleDifferenceH are making the jump (which is why at the moment of the jump the angle of the hour hand to the y-axis is the same as the angle of the minute hand to the x-axis), but angleDifferenceH doesn't need to make the jump. Change this:
float angleDifferenceH = angleDifferenceM * (1.0/12.0);
to
float angleDifferenceH = arcTanHour + angleDifferenceM * (1.0/12.0);
with an appropriate starting value for arcTanHour.