Question

I am trying to get a random color. I have done it using brute force but this method seems overly laborious (though the distribution is pretty even):

- (UIColor *) getRandomColor {
 // GOAL: reject colors that are too dark
 float total = 3;
 float one = arc4random() % 256 / 256.0;
 total -= one;
 float two = arc4random() % 256 / 256.0;
 total -= two;
 float three = total; // UIColor will chop out-of-range nums

 NSMutableArray *threeFloats = [[[NSMutableArray alloc] initWithObjects:[NSNumber numberWithFloat:one], [NSNumber numberWithFloat:two], [NSNumber numberWithFloat:three], nil] autorelease];

 NSNumber *red, *green, *blue;
 red = [threeFloats objectAtIndex:arc4random() % [threeFloats count]];
 [threeFloats removeObject:red];
 green = [threeFloats objectAtIndex:arc4random() % [threeFloats count]];
 [threeFloats removeObject:green];
 blue = [threeFloats lastObject];

 return [UIColor colorWithRed:[red floatValue] green:[green floatValue] blue:[blue floatValue] alpha:1];
}

How can it be bettered? I want an even distribution of red, green and blue and nothing too dark (otherwise I’d grab three random numbers and be done with it).

Answer 1

+ (UIColor *)colorWithHue:(CGFloat)hue saturation:(CGFloat)saturation brightness:(CGFloat)brightness alpha:(CGFloat)alpha;

CGFloat hue = ( arc4random() % 256 / 256.0 );  //  0.0 to 1.0
CGFloat saturation = ( arc4random() % 128 / 256.0 ) + 0.5;  //  0.5 to 1.0, away from white
CGFloat brightness = ( arc4random() % 128 / 256.0 ) + 0.5;  //  0.5 to 1.0, away from black

If white is ok then do saturation like hue instead of brightness.