Unable to change navigation bar opacity

问题:

I am trying to style my app in the following way, however i am unable to get my navigation bar to reach this level of opacity

I use the following code to style the navigation bar:

unc application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    UINavigationBar.appearance().barTintColor = UIColor(red: 1, green: 1, blue: 1, alpha: 0.1)
    UINavigationBar.appearance().tintColor = UIColor.whiteColor()
    UINavigationBar.appearance().titleTextAttributes = [NSForegroundColorAttributeName : UIColor.whiteColor()]
}

Even with the alpha set to 0.1, i still only get the following result:

Is it possible to achieve such a low opacity?

回答1:

This is the best way that I've found. You can just paste it into your appDelegate's didFinishLaunchingWithOptions method:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    // Sets background to a blank/empty image
    UINavigationBar.appearance().setBackgroundImage(UIImage(), forBarMetrics: .Default)
    // Sets shadow (line below the bar) to a blank image
    UINavigationBar.appearance().shadowImage = UIImage()
    // Sets the translucent background color
    UINavigationBar.appearance().backgroundColor = UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.0)
    // Set translucent. (Default value is already true, so this can be removed if desired.)
    UINavigationBar.appearance().translucent = true

    return true
}