navigationController规则不适用于ViewController

Question

My problem is with the navigationController the rules just don't apply.

 override func viewDidLoad() {
    super.viewDidLoad()
    navigationBarColor()
}

func navigationBarColor() {
        navigationController?.navigationBar.barTintColor = UIColor(red:0.91, green:0.04, blue:0.51, alpha:1.0)
        navigationController?.navigationBar.shadowImage = UIImage()
        navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
    }

Here's the result - The color is not there

What should I do?

Answer 1

Your code setting the style properties looks correct. It's likely that navigationController is nil.

A better approach is to use a custom navigation controller subclass and connect it to the navigation controller in Interface builder.

open class NavigationController: UINavigationController {
    open override func viewDidLoad() {
        super.viewDidLoad()
        navigationBar.barTintColor = UIColor.blue
    }
}

Answer 2

first you set bartintColor and after that you set the "clear image" in navigation bar :) of course it is be transparent.

you need image with some color or create it in code: (for example)

extension UIImage {

class func imageWithColor(_ color: UIColor) -> UIImage {
    let rect = CGRect(origin: CGPoint.zero, size: CGSize(width: 1.0, height: 1.0))
    UIGraphicsBeginImageContext(rect.size);

    guard let context = UIGraphicsGetCurrentContext() else {
        UIGraphicsEndImageContext()
        return UIImage()
    }

    context.setFillColor(color.cgColor);
    context.fill(rect);

    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return image ?? UIImage()
    }
}

and set image in navigation bar like this:

call this navigationBar changes when controller will appearing

    func updatenavigationBar() {
        navigationController?.navigationBar.tintColor = .white
        navigationController?.navigationBar.isTranslucent = true
        navigationController?.navigationBar.setBackgroundImage(UIImage.imageWithColor(color), for: .default)
        navigationController?.navigationBar.shadowImage = UIImage()
    }

Answer 3

I'm not quite sure what you're asking based on the question but if you are trying to change the color of the navigation bar I would suggest changing :

navigationController?.navigationBar.barTintColor = UIColor(red:0.91, green:0.04, blue:0.51, alpha:1.0)

To:

navigationController?.navigationBar.backgroundColor = UIColor(red:0.91, green:0.04, blue:0.51, alpha:1.0)

This will add the color as the background color instead of just the tint color.

Answer 4

Use this code

import Foundation
    import Swift

    extension UINavigationController
    {
        func setMainTopNavigationBarAttribute() -> Void
        {
            self.navigationBar.shadowImage = UIImage()
            self.navigationBar.setBackgroundImage(UIImage(), for: .default)
            self.navigationBar.isTranslucent = false
            self.navigationBar.tintColor = UIColor.white
            self.navigationBar.backgroundColor = UIColor.white
        }
    }

You can use this way

 let navigationController = UIStoryboard.user.instantiateViewController(withIdentifier: "MMNavigationController") as! UINavigationController
 navigationController.setMainTopNavigationBarAttribute()

Answer 5

You just change this two line in your function


func navigationBarColor() {

navigationController?.navigationBar.barTintColor = UIColor(red:0.91, green:0.04, blue:0.51, alpha:1.0)

//change this two line in your function
navigationController?.navigationBar.shadowImage = UIImage.init(named: "")
       navigationController?.navigationBar.setBackgroundImage(UIImage.init(named: ""), for: .default)
    }