Swift 隐藏导航栏，变色动画

透明

只需设置NavigationBar的背景图片为一张空图片便可

//设置导航栏透明
        self.navigationController?.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: UIBarMetrics.Default)
        self.navigationController?.navigationBar.shadowImage = UIImage()

 

变色动画

在NavigationBar下插入一个view，执行动画改变这个view的透明度便可。

let frame = self.navigationController?.navigationBar.frame
        let alphaView = UIView(frame: CGRect(x: 0, y: -20, width: frame!.size.width, height: frame!.size.height+20))
        alphaView.backgroundColor = UIColor.blueColor()
        alphaView.userInteractionEnabled = false
        self.navigationController?.navigationBar.insertSubview(alphaView, atIndex: 0)