Set a faded darker background to a UINavigationBar

问题

I'm trying to set a faded darker background to a navigation bar, as you can see on the image below.

I've tried with this code but it's not exactly what I expect.

UINavigationBar.appearance().backgroundColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.4)

I've found this topic, but without suitable answer:

Shows a faded gray color view through iOS 7 Navigation bar of a UISplitViewController

Any idea will be appreciated.

EDIT 6 oct 2015 : If somebody needs to know how to perform that

For Swift users : - in particular viewcontroller : i use :

 self.navigationController!.navigationBar.setBackgroundImage(UIImage(named: "fadedimage.png"), forBarMetrics: .Default)

in the main NavigationController (to apply that to the all navigationBar) i use :

UINavigationBar.appearance().setBackgroundImage(UIImage(named: "fadedimage.png"), forBarMetrics: .Default)

回答1:

This might not be the correct way, but you can achieve the same by using a custom image.

Donwload a transparent image from internet, I named it as transparent.png

and set the navigation bar background image:

[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"transaprent.png" ] forBarMetrics:UIBarMetricsDefault];

[self.navigationController.navigationBar setBackgroundColor:[UIColor colorWithRed:0.0f green:0.0f blue:0.0f alpha:0.0f]];

This gives the result:

Later you can apply the shadow effect for the navigation bar.

Edit:

I donwloaded a custom shadow transparent png image, and applied it using above code.

You can still improve this with a better custom image as per your requirements.

Here is the image I used:

To remove the bottom border that appears on navbar, use this code:

    [self.navigationController.navigationBar setShadowImage:[[UIImage alloc] init]];

来源：https://stackoverflow.com/questions/32955102/set-a-faded-darker-background-to-a-uinavigationbar