Check if UIColor is dark or bright?

Question

I need to determine whether a selected UIColor (picked by the user) is dark or bright, so I can change the color of a line of text that sits on top of that color, for better

Answer 1

If you prefer the block version:

BOOL (^isDark)(UIColor *) = ^(UIColor *color){
    const CGFloat *component = CGColorGetComponents(color.CGColor);
    CGFloat brightness = ((component[0] * 299) + (component[1] * 587) + (component[2] * 114)) / 1000;

    if (brightness < 0.75)
        return  YES;
    return NO;
};

Answer 2

- (BOOL)isColorLight:(UIColor*)color
{
    CGFloat white = 0;
    [color getWhite:&white alpha:nil];
    return (white >= .85);
}

Added Swift 5 version:

var white: CGFloat = 0.0
color.getWhite(&white, alpha: nil)
return white >= .85 // Don't use white background