Radial Gradient

gradient.m

- (void)drawRect:(CGRect)rect
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    const CGFloat components[8] = {0.0, 0.4, 0.0, 1.0,
                                   0.0, 0.4, 0.0, 1.0};
    const CGFloat locations[2] = {0.0, 1.0};
    CGGradientRef gradient = CGGradientCreateWithColorComponents(colorSpace, components, locations, 2);
    
    CGPoint startCenter = CGPointMake(100.0, 100.0);
    CGPoint endCenter = CGPointMake(100.0, 100.0);
    CGFloat startRadius = 0.0;
    CGFloat endRadius = 22.0;
    CGContextDrawRadialGradient(context,
                                gradient,
                                startCenter,
                                startRadius,
                                endCenter,
                                endRadius,
                                0);
}