How to change the color of the intersection of the circles

Question

I want to change the color of the intersection of the two circles.

I now use this method:

- (void)drawRect:(CGRect)rect{
    // draw circle 1
    CGRect circle1=CGRectMake(100, 200, 80, 80);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextAddArc(ctx, CGRectGetMinX(circle1), CGRectGetMinY(circle1), CGRectGetWidth(circle1)/2, 0, 2*M_PI, 1);
    CGContextSetFillColorWithColor(ctx, [UIColor blackColor].CGColor);
    CGContextDrawPath(ctx, kCGPathFill);

    // draw circle 2
    CGRect circle2=CGRectMake(170, 200, 80, 80);
    CGContextAddArc(ctx, CGRectGetMinX(circle2), CGRectGetMinY(circle2), CGRectGetWidth(circle2)/2, 0, 2*M_PI, 1);
    CGContextSetFillColorWithColor(ctx, [UIColor blackColor].CGColor);
    CGContextDrawPath(ctx, kCGPathFill);

    // intersection Rect
    CGRect intersectionRect=CGRectIntersection(circle1, circle2);
}

to get the intersection location, but what to do next?

As shown, I want to change the intersection of the two black circles to white.

intersection image

Can you provide the code for how you are drawing the circles? Are they views with rounded edges or are you using `addEllipse`? — Anters Bear, May 19 '18 at 04:18
@ch.chay may be this will helps you.. https://stackoverflow.com/questions/6757517/how-to-determine-intersection-of-cgpaths — Nirav Kotecha, May 19 '18 at 12:27

Anters Bear · Answer 1 · 2018-05-19T04:30:13.740

0

If they are circles.

If they are recatangles:

    let v1 = UIView()
    v1.frame = CGRect(x: 50, y: 50, width: 100, height: 100)
    v1.backgroundColor = UIColor.blue
    self.view.addSubview(v1)

    let v2 = UIView()
    v2.frame = CGRect(x: 100, y: 100, width: 100, height: 100)
    v2.backgroundColor = UIColor.yellow
    self.view.addSubview(v2)

    let v3 = UIView()
    v3.frame = v1.frame.intersection(v2.frame)
    v3.backgroundColor = UIColor.green
    self.view.addSubview(v3)

edited May 19 '18 at 04:30

answered May 19 '18 at 03:58

Anters Bear

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This will not work. This will change the color outside the circle, – ch.chay May 19 '18 at 04:08
Sry question was edited before you didn't mention circles you just said views. It will be much more complicated to do with circles / shapes... – Anters Bear May 19 '18 at 04:14

How to change the color of the intersection of the circles

1 Answers1