透明的UINavigationBar无边框

Question

With iOS 7, it's now pretty easy to add a blur to UINavigationBar, even with a BarTint, see http://blog.ashleynh.me/frosted-uinavigationbar/ and this example image:

However, there's a border at the bottom. How can I get rid of the border to look more like this?

UPDATE :

I took Danny and Shali's code, and here are the results. As you can see, the border doesn't show any more but there is no blur.

let navigationBarAppearance = UINavigationBar.appearance()
navigationBarAppearance.setBackgroundImage(UIImage(), forBarMetrics: UIBarMetrics.Default)
navigationBarAppearance.shadowImage = UIImage()
navigationBarAppearance.translucent = true

and here's the Inspector screenshot:

I also tried:

let navigationBarAppearance = UINavigationBar.appearance()
let clearImage = UIImage.imageWithColor(UIColor.clearColor())
navigationBarAppearance.setBackgroundImage(clearImage, forBarMetrics: UIBarMetrics.Default)
navigationBarAppearance.shadowImage = clearImage
navigationBarAppearance.translucent = true

Same result, but the Inspector is a little different:

Answer 1

Apple Documents: https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UINavigationBar_Class/index.html#//apple_ref/occ/instp/UINavigationBar/shadowImage

The default value is nil, which corresponds to the default shadow image. When non-nil, this property represents a custom shadow image to show instead of the default. For a custom shadow image to be shown, a custom background image must also be set with the setBackgroundImage:forBarMetrics: method. If the default background image is used, then the default shadow image will be used regardless of the value of this property.

So basically you need to set background image before setting shadowImage to make it work.

Edit

Image generated from color (Swift) as background Navigation. Not sure if your blur function will still work when you change backgroundImage for Navigation bar. That would be a different problem.

class func imageWithColor(color: UIColor) -> UIImage {
    let rect = CGRectMake(0, 0, 1, 1)
    UIGraphicsBeginImageContextWithOptions(rect.size, false, 0)
    color.setFill()
    UIRectFill(rect)
    var image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return image
}

Answer 2

Have you tried navigationBar.shadowImage = [UIImage new]; ?