Create Direction Arrows (arrow heads) on polyline in obj c - ios

Question

I have been searching for a quite while but couldn't find any answer to this, anyways, I am working on Google Maps for iOS using Obj C and have drawn routes (polyline) using multiple coordinates provided to me by the server in the form of an array. But the problem is that I want to show arrow heads on that line so that the direction can be seen on the map. Please help.

Answer 1

Here's a function which draws a nice little arrow line. It has some parameters you can tweak:
void TRDrawLineWithArrow(CGContextRef CXT, CGPoint FROMPOINT, CGPoint TOPOINT, CGFloat WIDTH, CGFloat ARROWSIZEMULTIPLE)
{
CGFloat rise = TOPOINT.y - FROMPOINT.y;
CGFloat run = TOPOINT.x - FROMPOINT.x;
// trig
CGFloat length = sqrt(rise*rise + run+run);
CGFloat angle = atan2(rise, run);
// the length of our arrowhead
CGFloat arrowLen = WIDTH*ARROWSIZEMULTIPLE;
// push graphics context
CGContextSaveGState(CXT);
// transform context according to line's origin and angle
CGContextTranslateCTM(CXT, FROMPOINT.x, FROMPOINT.y);
CGContextRotateCTM(CXT, angle);
// draw straight line
CGContextMoveToPoint(CXT, 0, -WIDTH/2.);
CGContextAddLineToPoint(CXT, 0, WIDTH/2.);
CGContextAddLineToPoint(CXT, length-arrowLen, WIDTH/2.);
// draw arrowhead
CGContextAddLineToPoint(CXT, length-arrowLen, (WIDTH*ARROWSIZEMULTIPLE)/2.);
CGContextAddLineToPoint(CXT, length, 0);
CGContextAddLineToPoint(CXT, length-arrowLen, -(WIDTH*ARROWSIZEMULTIPLE)/2.);
CGContextAddLineToPoint(CXT, length-arrowLen, -WIDTH/2.);
CGContextAddLineToPoint(CXT, 0, -WIDTH/2.);
// fill the path
CGContextFillPath(CXT);
// pop graphics context
CGContextRestoreGState(CXT);
}
You would call it from a UIView like this:
CGContextRef cxt = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(cxt, [UIColor blackColor].CGColor);
TRDrawLineWithArrow(cxt, CGPointMake(10,10), CGPointMake(300,100), 5, 3);