UIColor and Graphics Context

Question

I have a custom UIView which draws a path like so

- (void)drawRect:(CGRect)rect{

    [[UIColor blackColor] setStroke];
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextSetFillColor(ctx, CGColorGetComponents(self.color));

    CGContextFillPath(ctx);

    UIBezierPath *thePath = [UIBezierPath bezierPath];
    thePath.lineWidth = _lineWidth;

    _center = CGPointMake(rect.size.width, rect.size.height);

    [thePath moveToPoint:_center];

    [thePath addArcWithCenter:_center radius:rect.size.width startAngle:M_PI endAngle:M_PI+degreesToRadians(_angle)clockwise:YES];

    [thePath closePath];
    [thePath fill];

}

My custom UIView also has a method to change the filling color

- (void) changeColor:(UIColor *) newColor {

    self.color = [newColor CGColor];
    [self setNeedsDisplay];

}

If I call the changeColor: method with any of the predefined colors such as

 [UIColor redColor]  

everything works fine. Instead if i try to give it a custom color such as

 UIColor* color = [UIColor colorWithRed:1.0f green:0.0f blue:0.0f alpha:1.0f];

the color of my custom UIView flicker between white, red and blue randomly.

Any ideas of why is that?

Thank you in advance!

Answer 1

Try:

CGContextSetFillColorWithColor(ctx, self.color.CGColor);

instead of:

CGContextSetFillColor(ctx, CGColorGetComponents(self.color));

Answer 2

When you are using this method call :

[UIColor redColor];

For optimization purposes, UIColor return an object with only 2 components because he don't need the other one. (This is made possible with the mechanism of Class clustering).

That's maybe why your code show some differences between this two colors.