iOS 设置导航条透明效果的实例代码

//设置导航栏透明 
 func setNavigationIsTranslucent(isTranslucent:Bool) { 
   if isTranslucent == true { 
     self.navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default) 
     self.navigationController?.navigationBar.shadowImage = UIImage() 
     navigationController?.navigationBar.barStyle = .black 
   }else { 
     navigationController?.navigationBar.setBackgroundImage(UIImage(named: "nav_bg"), for: .default) 
     navigationController?.navigationBar.shadowImage = UIImage() 
     navigationController?.navigationBar.barStyle = .black 
   } 
 }