Restore default navigation bar appearance

问题:

I'm making an iOS app for iPhone, and I'm using a navigation controller. At some point during the navigation, I'm adding a UISegmentedControl to a view controller, just under the navigation bar from the navigation controller. I'm inserting new background and shadow images in the navigation bar, to make the UISegmentedControl appear as part of the navigation bar. I do it like this:

    // nav bar color image
    let rect = CGRectMake(0, 0, view.frame.width, 0.5)          // Used in navBar, size dosn't matter
    UIGraphicsBeginImageContextWithOptions(rect.size, true, 0)
    barBackgroundColor.setFill()
    UIRectFill(rect)
    let navBarBackground = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    // setup navbar
    navigationController!.navigationBar.setBackgroundImage(navBarBackground, forBarMetrics: .Default)
    navigationController!.navigationBar.shadowImage = UIImage()
    navigationController!.navigationBar.tintColor = UIColor.blackColor()
    navigationController!.navigationBar.translucent = false

When I navigate away from that given view controller, the navigation bars background is still changed.

How can I restore the navigation bars appearance?

Or...

Is there another way embed the UISegmentedControl into an expanded navigation bar?

Image of navigation bar with custom background and Segmented Control below:

When navigating back, the navigation bar cuntinues to be custom:

EDIT:

In a view controller before i change the background images, i try to safe the standart image:

override func viewDidAppear(animated: Bool) {

    if sharedVariables.standartNavBarBackgroundImage == nil {
        let herp = navigationController!.navigationBar.backgroundImageForBarMetrics(.Default)
        sharedVariables.standartNavBarBackgroundImage = herp
        let derp = navigationController!.navigationBar.shadowImage
        sharedVariables.standartNavBarShadowImage = derp
    }
}

Both herp and derp are nil after being set, dispite the navigationbar is visible at this momont. How come?

回答1:

You should be able to get the default appearance back just by setting the background image and shadow image to nil.

回答2:

With iOS 11.* and Swift 4, you need to set the barTintColor to nil.

navigationController?.navigationBar.barTintColor = nil