** My Bronze solution **


#1

very nice random colors using arc4random

[code]- (void)drawRect:(CGRect)rect
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGRect bounds = [self bounds];

CGPoint center;
center.x = bounds.origin.x + bounds.size.width / 2.0;
center.y = bounds.origin.y + bounds.size.height / 2.0;

float maxRadius = hypotf(bounds.size.width, bounds.size.height) / 2.0;

CGContextSetLineWidth(ctx, 10);
for (float currentRadius = maxRadius; currentRadius > 0; currentRadius -= 20) {
    CGContextAddArc(ctx, center.x, center.y, currentRadius, 0.0, M_PI * 2.0, YES);
    float r = arc4random() % 11 * 0.1;
    float g = arc4random() % 11 * 0.1;
    float b = arc4random() % 11 * 0.1;

    [self setCircleColor:[UIColor colorWithRed:r green:g blue:b alpha:1]];
    [[self circleColor] setStroke];
    
    CGContextStrokePath(ctx);
    
}[/code]

//the rest of the stuff