draw uiimage along CGMutablePathRef - uiimage

Question

How do i draw a custom uiimage along a CGMutablePathRef ? I can get the points from CGMutablePathRef but it does not give the smooth points that create the path.
I want to know if i can extract all of them plus the one that creat the smooth path.
i've used CGPathApply but i only get the control points, and when i draw my image it does not stay smooth as the original CGMutablePathRef
void pathFunction(void *info, const CGPathElement *element){
if (element->type == kCGPathElementAddQuadCurveToPoint)
{
CGPoint firstPoint = element->points[1];
CGPoint lastPoint = element->points[0];
UIImage *tex = [UIImage imageNamed:#"myimage.png"];
CGPoint vector = CGPointMake(lastPoint.x - firstPoint.x, lastPoint.y - firstPoint.y);
CGFloat distance = hypotf(vector.x, vector.y);
vector.x /= distance;
vector.y /= distance;
for (CGFloat i = 0; i < distance; i += 1.0f) {
CGPoint p = CGPointMake(firstPoint.x + i * vector.x, firstPoint.y + i * vector.y);
[tex drawAtPoint:p blendMode:kCGBlendModeNormal alpha:1.0f];
}
}
}

Answer 1

It seems like you are looking for the function that is used to draw a cubic Bézier curve from a start point and an end point and two control points.
start⋅(1-t)^3 + 3⋅c1⋅t(1-t)^2 + 3⋅c2⋅t^2(1-t) + end⋅t^3
By setting a value for t between 0 and 1 you will get a point on the curve at a certain percentage of the curve length. I have a short description of how it works in the end of this blog post.
Update
To find the point to draw the image somewhere between the start and end points you pick a t (for example 0.36 and use it to calculate the x and y value of that points.
CGPoint start, end, c1, c2; // set to some value of course
CGFloat t = 0.36;
CGFloat x = start.x*pow((1-t),3) + 3*c1.x*t*pow((1-t),2) + 3*c2.x*pow(t,2)*(1-t) + end.x*pow(t,3);
CGFloat y = start.y*pow((1-t),3) + 3*c1.y*t*pow((1-t),2) + 3*c2.y*pow(t,2)*(1-t) + end.y*pow(t,3);
CGPoint point = CGPointMake(x,y); // this is 36% along the line of the curve
Which given the path in the image would correspond to the orange circle
If you do this for many points along the curve you will have many images positioned along the curve.
Update 2
You are missing that kCGPathElementAddQuadCurveToPoint (implicitly) has 3 points: start (the current/previous points, the control point (points[0]) and the end point (points[1]). For a quad curve both control points are the same so c1 = c2;. For kCGPathElementAddCurveToPoint you would get 2 different control points.