Question

Possible Duplicate:
UINavigationBar gradient details

I looked around the web but I haven’t found a clear example. I have no experience with CGGradient but I need a very simple thing:
I want add a gradient to the NavigationBar of my NavigationController, the gradient should be linear, from top to bottom. I want the start color to be : (88.0, 38.0, 40.0) and the end color (50.0 15.0 16.0). Could you please give me an example of how I could add this gradient to my navigation bar?

Thank you

Answer 1

adjust the color or supply a image if you want

//                                  #Lighter r,g,b,a                    #Darker r,g,b,a
#define MAIN_COLOR_COMPONENTS       { 0.153, 0.306, 0.553, 1.0, 0.122, 0.247, 0.482, 1.0 }
#define LIGHT_COLOR_COMPONENTS      { 0.478, 0.573, 0.725, 1.0, 0.216, 0.357, 0.584, 1.0 }

@implementation UINavigationBar (UINavigationBarCategory)

- (void)drawRect:(CGRect)rect {
    if (imageReady) {
        UIImage *img = [UIImage imageNamed: @"navigation_background.png"];
        [img drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
    } else {
        // Render yourself instead.
        // You will need to adjust the MAIN_COLOR_COMPONENTS and LIGHT_COLOR_COMPONENTS to match your app

       // emulate the tint colored bar
       CGContextRef context = UIGraphicsGetCurrentContext();
       CGFloat locations[2] = { 0.0, 1.0 };
       CGColorSpaceRef myColorspace = CGColorSpaceCreateDeviceRGB();

       CGFloat topComponents[8] = LIGHT_COLOR_COMPONENTS;
       CGGradientRef topGradient = CGGradientCreateWithColorComponents(myColorspace, topComponents, locations, 2);
       CGContextDrawLinearGradient(context, topGradient, CGPointMake(0, 0), CGPointMake(0,self.frame.size.height/2), 0);
       CGGradientRelease(topGradient);

       CGFloat botComponents[8] = MAIN_COLOR_COMPONENTS;
       CGGradientRef botGradient = CGGradientCreateWithColorComponents(myColorspace, botComponents, locations, 2);
       CGContextDrawLinearGradient(context, botGradient,
       CGPointMake(0,self.frame.size.height/2), CGPointMake(0, self.frame.size.height), 0);
       CGGradientRelease(botGradient);

       CGColorSpaceRelease(myColorspace);


       // top Line
       CGContextSetRGBStrokeColor(context, 1, 1, 1, 1.0);
       CGContextMoveToPoint(context, 0, 0);
       CGContextAddLineToPoint(context, self.frame.size.width, 0);
       CGContextStrokePath(context);

       // bottom line
       CGContextSetRGBStrokeColor(context, 0, 0, 0, 1.0);
       CGContextMoveToPoint(context, 0, self.frame.size.height);
       CGContextAddLineToPoint(context, self.frame.size.width, self.frame.size.height);
       CGContextStrokePath(context);
    }
}

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