iOS - UIBarButtonItem Identifier - option to create "settings" cogwheel button

Unicode has several notable examples you can simply copy and paste into a string declaration in Xcode, or use the standard Unicode String Escape (\uxxxx) and iOS is actually quite fluent when it comes to Unicode (I know some of the char's are fairly ugly, but that's Unicode for ya'):

Unicode Character 'GEAR WITHOUT HUB' (U+26ED): http://www.fileformat.info/info/unicode/char/26ed/index.htm

Unicode Character 'GEAR' (U+2699): http://www.fileformat.info/info/unicode/char/2699/index.htm

Or prepare an image and set the UIBarButtonItem's customView property accordingly.

This works in Swift 5 and iOS 14.4...

    let settingsButton = UIBarButtonItem(title: NSString(string: "\u{2699}\u{0000FE0E}") as String, style: .plain, target: self, action: #selector(self.settingsBtn(_:)))
    let font = UIFont.systemFont(ofSize: 28) // adjust the size as required
    let attributes = [NSAttributedString.Key.font : font]
    settingsButton.setTitleTextAttributes(attributes, for: .normal)
    self.navigationItem.rightBarButtonItem = settingsButton

See @hazelnut's comment in the accepted answer. Without adding \u{0000FE0E} to the string it shows up as an emoji and is immune to any appearance settings. Adding that string fixes that.

Composing CodaFi and user1046037 answers:

Creating UIBarButtonItem with unicode character as a title.

You have to initialize UIBarButtonItem with title (initWithTitle:) not system item (initWithBarButtonSystemItem:).

You can set custom title with string (such as unicode character).

You can resize title.

UIBarButtonItem *settingsButton = [[UIBarButtonItem alloc] initWithTitle:@"\u2699" style:UIBarButtonItemStylePlain target:self action:@selector(showSettings)];

UIFont *customFont = [UIFont fontWithName:@"Helvetica" size:24.0];
NSDictionary *fontDictionary = @{NSFontAttributeName : customFont};
[settingsButton setTitleTextAttributes:fontDictionary forState:UIControlStateNormal];