cylindrical look Gradient in UIView - objective-c

Question

I want to draw bar with a cylindrical look and with shadow effect(As shown in the below image). Can some one help to define Linear Gradient for below look and feel.
Code:
-(void)drawRect:(CGRect)rect {
//UIview Back color is red or green
CGGradientRef glossGradient;
CGColorSpaceRef rgbColorspace;
CGContextRef currentContext = UIGraphicsGetCurrentContext();
size_t num_locations = 4;
CGFloat locations[4] = { 0.0,0.7,0.9,1.0 };
CGFloat components[16] = { 0.0, 0.0, 0.0, 0.01,
0.0, 0.0, 0.0, 0.1,
0.0, 0.0, 0.0, 0.2,
0.0, 0.0, 0.0, 0.5
};
rgbColorspace = CGColorSpaceCreateDeviceRGB();
glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);
CGRect currentBounds = self.bounds;
CGPoint topCenter = CGPointMake(CGRectGetMidX(currentBounds), 0.0f);
CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), currentBounds.size.height);
CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, 0);
CGGradientRelease(glossGradient);
CGColorSpaceRelease(rgbColorspace);
}

Answer 1

Here's a general purpose gradient maker:
CGGradientRef makeGradient2(NSArray *colors, CGFloat *stops)
{
size_t nc = 4;
NSInteger colorSize = nc * sizeof(CGFloat);
CGFloat *theComponents = malloc( [colors count] * colorSize );
CGFloat *compPtr = theComponents;
for (int i=0; i < colors.count; i++){
UIColor *color = [colors objectAtIndex:i];
CGColorRef cgColor = [color CGColor];
const CGFloat *components = CGColorGetComponents(cgColor);
memmove(compPtr, components, colorSize);
compPtr += nc;
}
CGColorSpaceRef cs = CGColorSpaceCreateDeviceRGB();
CGGradientRef gradient = CGGradientCreateWithColorComponents (cs, theComponents, stops, colors.count);
CGColorSpaceRelease(cs);
free(theComponents);
return gradient;
}
call it like (this creates a three part gray gradient with lightest in the middle)
CGFloat stops[] = { 0.0, 0.5, 1.0};
gradient = makeGradient2([NSArray arrayWithObjects:
[UIColor colorWithRed:.2 green:.2 blue:.2 alpha:1.0],
[UIColor colorWithRed:.5 green:.5 blue:.5 alpha:1.0],
[UIColor colorWithRed:.2 green:.2 blue:.2 alpha:1.0],
nil], stops);
and then you can draw with it like (for a left to right gradient):
CGContextDrawLinearGradient(gc, gradient, CGPointMake(0.0, 0.0), CGPointMake(rect.size.width, 0.0), 0);