UINavigationBar 下面的 黑线

iOS之navigationBar背景

iOS之navigationBar背景

让导航栏变透明，去掉导航栏下面的线

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iOS开发小结 - UINavigationBar设置shadowImage

        let size = self.navigationController!.navigationBar.frame.size
        UIGraphicsBeginImageContextWithOptions(size, false, UIScreen.mainScreen().scale)
        var context = UIGraphicsGetCurrentContext()
        UIColor.blueColor().setFill()
        CGContextAddRect(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, size.width, 2))
        CGContextDrawPath(context, .Fill)
        var image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        self.navigationController?.navigationBar.shadowImage = image

        UIGraphicsBeginImageContextWithOptions(CGSizeMake(size.width, size.width+20), false, UIScreen.mainScreen().scale)
        context = UIGraphicsGetCurrentContext()
        UIColor.redColor().setFill()
        CGContextAddRect(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, size.width, size.height+20))
        CGContextDrawPath(context, .Fill)
        image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        self.navigationController?.navigationBar.setBackgroundImage(image, forBarMetrics: .Default)