设置后退按钮颜色

Question

I have set all bar button items, including back buttons, with...

UIBarButtonItem.appearance.tintColor = UIColor.red

However, I want to override the back button color on one page but I cannot find a reference to a back button. All the references with the right sounding name are null.

Why are they all null? Where does the back button come from?

Answer 1

Try it without using the appearance proxy. Set the main window's tintColor property to your default color. Then in your specific view controller's viewWillAppear / viewWillDisappear set / reset the specific color:

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow? {
        didSet {
            // set your default tint color
            window?.tintColor = .red
        }
    }

}

class SpecificViewController: UIViewController {

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        navigationController?.navigationBar.tintColor = .magenta
    }

    override func viewWillDisappear(_ animated: Bool) {
        navigationController?.navigationBar.tintColor = nil
        super.viewWillDisappear(animated)
    }

}

Results in:

Answer 2

What you should rather be doing is setting the navigationBar.tintColor .

UINavigationBar.appearance.tintColor = .red

This will apply the color to every navigation bar. So you have to set and reset it again in the view controller you want to change the color.

In viewWillAppear :

self.navigationContoller?.navigationBar.tintColor = .blue

In viewWillDisappear :

self.navigationController?.navigationBar.tintColor = .red