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Asked: 2026-06-09T23:27:15+00:00

I’ve been trying to draw a triangle in Core Graphics for some time. I’ve

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I’ve been trying to draw a triangle in Core Graphics for some time. I’ve figured out how to by I’m not quite sure if it is the best way.

I also can’t figure out how to center it in the UIView

Here is my code

CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path, NULL,10, 100);
CGPathAddLineToPoint(path, NULL,100,10);
CGPathAddLineToPoint(path, NULL,200,100);
CGPathAddLineToPoint(path, NULL,100,100);
CGPathCloseSubpath(path);

CGContextSetFillColorWithColor(context, white);
CGContextAddPath(context, path);
CGContextFillPath(context);
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1 Answer

  1. Editorial Team

    To center your triangle, you would have to do a little math — there are actually several “centers” of triangles, but the one where you draw a line from each vertex to the center of the opposite line, defines the center as where these lines cross. This center is easy to find, by averaging the x values and the y values — so in your case where you have (10,100), (100,10) and (200,100) as your vertices, the center would be (10+100+200/3 , 100+10+100/3) or (103.3,70). The full screen of an iPhone, which is 320 wide by 460 high, has its center at (160,230). So basically, you need to add the difference between your triangles center and the screen center to each point — add 160-103.3 to each x value and 230-70 to each y point, and that will draw the same triangle, but centered in the screen.

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