1

可能重复：
UINavigationBar 渐变细节

我环顾网络，但我没有找到一个明确的例子。我没有使用 CGGradient 的经验，但我需要一个非常简单的东西：我想给我的 NavigationController 的 NavigationBar 添加一个渐变，渐变应该是线性的，从上到下。我希望起始颜色为：(88.0, 38.0, 40.0) 和结束颜色 (50.0 15.0 16.0)。你能给我一个例子来说明我如何将这个渐变添加到我的导航栏吗？

谢谢

4

3 回答 3

3

如果需要，可以调整颜色或提供图像

//                                  #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);
    }
}

资源

于 2012-03-07T10:00:48.193 回答
1

以下是用于设置导航图像的渐变。

@interface CustomNavigationBar : UINavigationBar
@end

@implementation CustomNavigationBar
-(void) drawRect:(CGRect)rect 
{
    UIImage *image = [UIImage imageNamed: @"myNavBarImage"];
    [image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
}
@end

// this can go anywhere
+(UINavigationController*) myCustomNavigationController
{
  MyViewController *vc = [[[MyViewController alloc] init] autorelease];
  UINavigationController *nav = [[[NSBundle mainBundle] loadNibNamed:@"CustomNavigationController" owner:self options:nil] objectAtIndex:0];
  nav.viewControllers = [NSArray arrayWithObject:vc];
  return nav;
}

您也可以下载这种实现演示的源代码

谢谢并恭祝安康

霓虹灯塞缪尔

于 2012-03-07T10:06:52.247 回答
-3

使用 tintColor 属性，

[self.navigationController.navigationBar setTintColor:[UIColor blackColor]];

它工作正常。想知道你是否需要进一步澄清

于 2012-03-07T10:00:48.337 回答