Weird result when comparing two colors with isEqual

Question

I'm trying to compare two colors but I can't get the correct result:

Here is my code:

NSLog(@"selfColor = %@",selfColor);
NSLog(@"left = %@",left);
NSLog(@"[selfColor isEqual:left] = %@",[selfColor isEqual:left] ? @"TRUE":@"FALSE");

And here is my debug log:

2016-01-05 16:58:24.050 breakout[84467:11799727] selfColor = UIDeviceRGBColorSpace 0.333333 0.333333 0.333333 1
2016-01-05 16:58:24.050 breakout[84467:11799727] left = UIDeviceRGBColorSpace 0.333333 0.333333 0.333333 1
2016-01-05 16:58:24.050 breakout[84467:11799727] [selfColor isEqual:left] = FALSE

The two colors are the same, but the isEqual: function still return false... What am I missing ?

Thanks for your help

Edit:

The colors are generated by this function from another SO question

BOOL isEqualToColor(UIColor *left, UIColor *right) {
CGColorSpaceRef colorSpaceRGB = CGColorSpaceCreateDeviceRGB();

UIColor *(^convertColorToRGBSpace)(UIColor*) = ^(UIColor *color) {
    if (CGColorSpaceGetModel(CGColorGetColorSpace(color.CGColor)) == kCGColorSpaceModelMonochrome) {
        const CGFloat *oldComponents = CGColorGetComponents(color.CGColor);
        CGFloat components[4] = {oldComponents[0], oldComponents[0], oldComponents[0], oldComponents[1]};
        CGColorRef colorRef = CGColorCreate( colorSpaceRGB, components );

        UIColor *color = [UIColor colorWithCGColor:colorRef];
        CGColorRelease(colorRef);
        return color;
    } else
        return color;
};

UIColor *selfColor = convertColorToRGBSpace(right);
left = convertColorToRGBSpace(left);
CGColorSpaceRelease(colorSpaceRGB);

NSLog(@"selfColor = %@",selfColor);
NSLog(@"left = %@",left);
NSLog(@"[selfColor isEqual:left] = %@",[selfColor isEqual:left] ? @"TRUE":@"FALSE");

return [selfColor isEqual:left];
}

And I call it like this:

if (isEqualToColor(node.color,[UIColor darkGrayColor])) {...}

Consider that `[UIColor darkGrayColor]` has only two components (white and alpha) while most custom colors are created with 4 (red, green, blue, alpha) — vadian, Jan 05 '16 at 16:43

score 1 · Accepted Answer · answered Jan 05 '16 at 16:26

Here is a way to compare colors

-(BOOL)isColor:(UIColor *)first similarToColor:(UIColor *)second {
    float tolerance = 0.01; // 1%

    CGColorRef firstColor = [first CGColor];
    CGColorRef secondColor = [second CGColor];

    if (CGColorGetColorSpace(firstColor) != CGColorGetColorSpace(secondColor)) {
        return FALSE;
    }

    NSUInteger componentCount = CGColorGetNumberOfComponents(firstColor);

    const CGFloat *leftComponents = CGColorGetComponents(firstColor);
    const CGFloat *rightComponents = CGColorGetComponents(secondColor);

    for (int i = 0; i < componentCount; i++) {
        float difference = leftComponents[i] / rightComponents[i];

        if (fabs(difference - 1) > tolerance) {
            return FALSE;
        }
    }

    return TRUE;
}

And make the call

 [self isColor:selfColor similarToColor:left];

You can change the tolerance value if you want a test more or less accurate

I finally got this working by merging your answer with my isEqualToColor function. Instead of using "return [selfColor isEqual:left]" I now call" return isColorSimilarToColor(selfColor,left)" and it works perfectly ! — Olivier PIERRE, Jan 07 '16 at 13:08

Weird result when comparing two colors with isEqual

1 Answers1