xcode 7.3 swift访问并更改导航栏中的颜色和文本

Question

I'm trying to learn how to access and change theme colors and fonts in one of my view controllers (UIViewController, with a nav bar added manually, no navigation controller is on my storyboard).

I've been partially successful with this code in my view controller viewDidLoad:

UINavigationBar.appearance().backgroundColor = theme.TabsColor
UINavigationBar.appearance().barTintColor = theme.NavColor

But this code from another post here on SO compiles/works, but has no effect:

self.navigationController?.navigationBar.translucent = false

And I have not been successful at even simple things, like changing the background color of nav bar items, with simple code like this:

for view1 in UINavigationBar.appearance().subviews {
  view1.backgroundColor = theme.CellColor
  for view2 in view1.subviews {
    view2.backgroundColor = theme.CellColor
    for view3 in view2.subviews {
      view3.backgroundColor = theme.CellColor
      for view4 in view3.subviews {
        view4.backgroundColor = theme.CellColor
      }
    }
  }
}

To find and color my StackView items, I give them a restorationIdentifer on the storyboard, then I can find them in my searching loops. But there's no restorationIdentifiers for Nav bars, so that method won't work.

How can I access and turn off .translucent in a nav bar from within my controller?

How can I access and modify colors and text properties of things on the nav bar that I added to my view controller? (I'm using nav bar without navigation controller.)

How can I access and modify colors and text on all nav bars (with nav controllers) in my whole app?

Thanks. I hope that isn't too many questions for one post, but all the questions get at the same thing -- how to access nav bars (with and without controllers) in swift 2.2.. (There are quite a few posts from 2011-2014 on ObjC nav bars, but they haven't been able to help me much.

UPDATE: I have made more progress in my understanding of nav bars.

The most obvious leap (that made me feel like a real newbie, which I am for xcode/swift) was that I could easily get a code reference to my nav bar simply by creating an outlet for it. Doh! Then I could reference it directly through the outlet, rather than by using convoluted references involving UINavigationBar or self.navigationController?.navigationBar, etc.

  @IBOutlet weak var NavBar: UINavigationBar!

Following that idea of just using simple outlets, it was also possible to reference the NavBar title in the same way, through an outlet.

@IBOutlet weak var NavTitle: UINavigationItem!

So this is the kind of code that works for changing NavBar and NavTitle background colors in Swift. (Actually, the backgroundColor code below seems useless, and has zero visual effect on my project. It's the barTintColor that actually changes the color of my NavBar.)

    // turning off translucent doesn't help
NavBar.translucent = false
NavBar.backgroundColor = theme.NavColor

// barTintColor actually colors the bar
NavBar.barTintColor = theme.NavColor
NavBar.tintColor = UIColor.redColor() // colors the builtin back arrow

So I can use outlets to reference NavBar and NavTitle (probably NavBarItems too), and can change the background of the NavBar using barTintColor (but not backgroundColor). I can change the color of the NavItem backItem with NavBar.tintColor.

But I still can't figure out how to change the color of the NavTitle text, its font, etc, either by using references like NavBar...whatever or NavTitle...whatever. I think the answer lies in the titleTextAttributes dictionary somehow, but I can't find code examples on the net or in the Apple (swift) doc. I tried the code below (cribbed from an ObjC posting here on SO), but it seemed useless (ineffective). So I'm still stuck on how to change foreground, background colors for title text, or the font, etc.

    //    NavBar.titleTextAttributes - I can't get it to work
NavTitle.title = "Using an outlet helps"
NavBar.titleTextAttributes?.updateValue(UIColor.blueColor(), forKey: NSForegroundColorAttributeName)

I undertook this whole NavBar project because I read somewhere that it was common to use NavBars just to display items and a title, without using them for their navigation smarts or properties.

But now after spending a couple of days trying to figure out how they work, I'm just going to abandon them for that purpose. It's just WAY easier to use a horizontal StackView or a Toolbar instead. Hopefully someone can benefit from this long posting one day...

ANOTHER UPDATE:

I'm beginning to wonder if it's even possible to reference a navigation bar from within a view controller, using syntax that starts with "self.view.xxx." Here's a screenshot of the controller view hierarchy, taken at a debug breakpoint in viewDidLoad. I can see all the UIViews on the controller page, except for the nav bar.

So maybe the only way to reference nav bars is (1) with UINavigationBar.xxx to use a global class reference of some kind, or (2) use an IBOutlet, created with the storyboard, to reference the nav bar directly.

Answer 1

Here's the answer for Xcode 7.3. To set the title text color for a navigation bar:-

Put this into AppDelegate didFinishLaunchingWithOptions

    if let _ = UINavigationBar.appearance().titleTextAttributes {
        print("setting textAttributes")
        UINavigationBar.appearance().titleTextAttributes?.updateValue(UIColor.whiteColor(), forKey: "TextColor")
    }
    else {
        print("textAttributes is nil")
        UINavigationBar.appearance().titleTextAttributes = ["TextColor" : UIColor.whiteColor()]
    }

Answer 2

I think you want the navigation bar to have color in order to do that you need to have Navigation Bar in the bottom left selected and in the top right you can change the bar tint which changes the Navigation Bar's color. Refer to the picture. http://i.stack.imgur.com/oRBpo.png

Answer 3

The answer is embedded in that long post above. For clarity and simplicity, I'll summarize it here.

To programmatically change NavBar colors, you can reference the NavBar in two ways: by using an explicit outlet in your view controller code to reference the nav bar, the nav title, or nav items. Or you can reference the global Nav bar with UINavigationBar.xxx.

But since the NavBar is not part of the object hierarchy below self.view, I was not able to create a self.view.xxx reference that worked.

I still don't know how to reference the text font, colors, size of the NavTitle. This is an issue if you pick a dark Nav Bar color and want to use white text on dark background (tint).