How to have a view travel the path of an inverted parabola? - iphone

Question

I have an inverted parabola and i need to have a view traverse through the path of the parabola.The view should slightly rotate and translate along the path of the parabola.
I did some research and found that BezierPath (quadcurve with control points) could be used to lay the path of the parabola out and then we could use CAKeyFramAnimation to move the object along the path.Animating the view object along the path of the parabola is whats confusing me.
How do i keep changing the starting points of the object within the parabola and retain the latest state of the view
Here's a brief description of what i want to achieve with the view in the parabola
The view starts from a particular point in the parabola and then traverses the parabola till the specified end point.
How do i find out the end point within the parabola?
Once the view reaches its end point.For the next traversal it can start from that point and then move on to any other point within the parabola.This happens continuously based on the next end point.
This is a rough sketch oh how the path and the view would look like
And also i would like both the rotation and translation of the view traversing the path to happen simultaneously
How can this be done?
Thank you!

Answer 1

Draw parabola with UIBezierPath and convert it to CGPath or Create a CGPath.
Use CAKeyFrameAnimation to move UIView's position.
Look at the below source code,
Drawing Parabola
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path,NULL,50.0,120.0);
CGPathAddCurveToPoint(path,NULL,50.0,275.0,
150.0,275.0,
150.0,120.0);
CGPathAddCurveToPoint(path,NULL,150.0,275.0,
250.0,275.0,
250.0,120.0);
CGPathAddCurveToPoint(path,NULL,250.0,275.0,
350.0,275.0,
350.0,120.0);
CGPathAddCurveToPoint(path,NULL,350.0,275.0,
450.0,275.0,
450.0,120.0);
CAKeyFrameAnimation along a path.
CAKeyframeAnimation* AniLoc = [CAKeyframeAnimation animationWithKeyPath:#"position"]; // notice key change
// rest is the same
AniLoc.path = thePath;
AniLoc.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];
AniLoc.keyTimes= [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0f],
[NSNumber numberWithFloat:0.3f],
[NSNumber numberWithFloat:1.0f],nil];
AniLoc.duration = 2.0;
CFRelease(thePath);
[self.logo.layer addAnimation:AniLoc forKey:nil];