Can't change UINavigationBar prompt color - ios

Question

I am unable to change the prompt color on my navigation bar. I've tried the code below in viewDidLoad, but nothing happens.
self.navigationController?.navigationBar.titleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.white]
Am I missing something? Is the code above wrong?

Answer 1

I was able to make the prompt color white on iOS 11 was setting the barStyle to black. I set the other color attributes (like the desired background color) using the appearance proxy:
myNavbar.barStyle = UIBarStyleBlack; // Objective-C
myNavbar.barStyle = .black // Swift

Answer 2

It seems like you're right about this one. You need to use UIAppearance to style the prompt text on iOS 11.
I've filed radar #34758558 that the titleTextAttributes property just stopped working for prompt in iOS 11.
The good news is that there are a couple of workarounds, which we can uncover by using Xcode's view hierarchy debugger:
// 1. This works, but potentially changes *all* labels in the navigation bar.
// If you want this, it works.
UILabel.appearance(whenContainedInInstancesOf: [UINavigationBar.self]).textColor = UIColor.white
The prompt is just a UILabel. If we use UIAppearance's whenContainedInInstancesOf:, we can pretty easily update the color the way we want.
If you look closely, you'll notice that there's also a wrapper view on the UILabel. It has its own class that might respond to UIAppearance...
// 2. This is a more precise workaround but it requires using a private class.
if let promptClass = NSClassFromString("_UINavigationBarModernPromptView") as? UIAppearanceContainer.Type
{
UILabel.appearance(whenContainedInInstancesOf: [promptClass]).textColor = UIColor.white
}
I'd advise sticking to the more general solution, since it doesn't use private API. (App review, etc.) Check out what you get with either of these two solutions:

Answer 3

You may use
for view in self.navigationController?.navigationBar.subviews ?? [] {
let subviews = view.subviews
if subviews.count > 0, let label = subviews[0] as? UILabel {
label.textColor = UIColor.white
label.backgroundColor = UIColor.red
}
}
It will be a temporary workaround until they'll fix it

Answer 4

More complicated version to support old and new iOS
func updatePromptUI(for state: State) {
if (state != .Online) {
//workaround for SOFT-7019 (iOS 11 bug - Offline message has transparent background)
if #available(iOS 11.0, *) {
showPromptView()
} else {
showOldPromptView()
}
}
else {
self.navigationItem.prompt = nil
if #available(iOS 11.0, *) {
self.removePromptView()
} else {
self.navigationController?.navigationBar.titleTextAttributes = nil
self.navigationController?.navigationBar.titleTextAttributes = [NSAttributedStringKey.foregroundColor:UIColor.lightGray]
}
}
}
private func showOldPromptView() {
self.navigationItem.prompt = "Network Offline. Some actions may be unavailable."
let navbarFont = UIFont.systemFont(ofSize: 16)
self.navigationController?.navigationBar.titleTextAttributes = [NSAttributedStringKey.font: navbarFont, NSAttributedStringKey.foregroundColor:UIColor.white]
}
private func showPromptView() {
self.navigationItem.prompt = String()
self.removePromptView()
let promptView = UIView(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 18))
promptView.backgroundColor = .red
let promptLabel = UILabel(frame: CGRect(x: 0, y: 2, width: promptView.frame.width, height: 14))
promptLabel.text = "Network Offline. Some actions may be unavailable."
promptLabel.textColor = .white
promptLabel.textAlignment = .center
promptLabel.font = promptLabel.font.withSize(13)
promptView.addSubview(promptLabel)
self.navigationController?.navigationBar.addSubview(promptView)
}
private func removePromptView() {
for view in self.navigationController?.navigationBar.subviews ?? [] {
view.removeFromSuperview()
}
}

Answer 5

I suggest using a custom UINavigationBar subclass and overriding layoutSubviews:
- (void)layoutSubviews {
[super layoutSubviews];
if (self.topItem.prompt) {
UILabel *promptLabel = [[self recursiveSubviewsOfKind:UILabel.class] selectFirstObjectUsingBlock:^BOOL(UILabel *label) {
return [label.text isEqualToString:self.topItem.prompt];
}];
promptLabel.textColor = self.tintColor;
}
}
Basically I'm enumerating all UILabels in the subview hierarchy and check if their text matches the prompt text. Then we set the textColor to the tintColor (feel free to use a custom color). That way, we don't have to hardcode the private _UINavigationBarModernPromptView class as the prompt label's superview. So the code is be a bit more future-proof.
Converting the code to Swift and implementing the helper methods recursiveSubviewsOfKind: and selectFirstObjectUsingBlock: are left as an exercise to the reader 😉.

Answer 6

You can try this:
import UIKit
class ViewController: UITableViewController {
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
updatePrompt()
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
updatePrompt()
}
func updatePrompt() {
navigationItem.prompt = " "
for view in navigationController?.navigationBar.subviews ?? [] where NSStringFromClass(view.classForCoder) == "_UINavigationBarModernPromptView" {
if let prompt = view.subviews.first as? UILabel {
prompt.text = "Hello Red Prompt"
prompt.textColor = .red
}
}
navigationItem.title = "This is the title (Another color)"
}
}

Answer 7

Moshe's first answer didn't work for me because it changed the labels inside of system VCs like mail and text compose VCs. I could change the background of those nav bars but that opens up a whole other can of worms. I didn't want to go the private class route so I only changed UILabels contained inside of my custom navigation bar subclass.
UILabel.appearance(whenContainedInInstancesOf: [NavigationBar.self]).textColor = UIColor.white

Answer 8

Try this out:->
navController.navigationBar.titleTextAttributes = [NSAttributedStringKey.foregroundColor.rawValue: UIColor.red]

Answer 9

I've found next work around for iOS 11.
You need set at viewDidLoad
navigationItem.prompt = UINavigationController.fakeUniqueText
and after that put next thing
navigationController?.promptLabel(completion: { label in
label?.textColor = .white
label?.font = Font.regularFont(size: .p12)
})
extension UINavigationController {
public static let fakeUniqueText = "\n\n\n\n\n"
func promptLabel(completion: #escaping (UILabel?) -> Void) {
gloabalThread(after: 0.5) { [weak self] in
guard let `self` = self else {
return
}
let label = self.findPromptLabel(at: self.navigationBar)
mainThread {
completion(label)
}
}
}
func findPromptLabel(at view: UIView) -> UILabel? {
if let label = view as? UILabel {
if label.text == UINavigationController.fakeUniqueText {
return label
}
}
var label: UILabel?
view.subviews.forEach { subview in
if let promptLabel = findPromptLabel(at: subview) {
label = promptLabel
}
}
return label
}
}
public func mainThread(_ completion: #escaping SimpleCompletion) {
DispatchQueue.main.async(execute: completion)
}
public func gloabalThread(after: Double, completion: #escaping SimpleCompletion) {
DispatchQueue.global().asyncAfter(deadline: .now() + after) {
completion()
}
}