How to apply a gradient on a UI Tab Bar In Swift?

问题

I built the tab bar through the storyboard, and to customise the colour I change it in the app delegate, with UITabBar.appearance().barTintColor = Color,

I have a gradient method which is this:

func setGradientBackground(colorOne: UIColor, colorTwo: UIColor)  {
    let gradientlayer = CAGradientLayer()
    gradientlayer.frame = bounds
    gradientlayer.colors = [colorOne.cgColor, colorTwo.cgColor]
    gradientlayer.locations = [0, 1]
    gradientlayer.startPoint = CGPoint(x: 1.0, y: 0.0)
    gradientlayer.endPoint = CGPoint(x: 0.0, y: 0.0)

    layer.insertSublayer(gradientlayer, at: 0)

}

How do I apply this to the background of my tab bar?

回答1:

Just create a subclass of UITabBarController

class GradientTabBarController: UITabBarController {

        let gradientlayer = CAGradientLayer()

        override func viewDidLoad() {
            super.viewDidLoad()
            setGradientBackground(colorOne: .yellow, colorTwo: .red)
        }

        func setGradientBackground(colorOne: UIColor, colorTwo: UIColor)  {
            gradientlayer.frame = tabBar.bounds
            gradientlayer.colors = [colorOne.cgColor, colorTwo.cgColor]
            gradientlayer.locations = [0, 1]
            gradientlayer.startPoint = CGPoint(x: 1.0, y: 0.0)
            gradientlayer.endPoint = CGPoint(x: 0.0, y: 0.0)
            self.tabBar.layer.insertSublayer(gradientlayer, at: 0)
        }
}

Assign GradientTabBarController class in the storyboard instead of UITabBarController

Main pros of this methodology are below.

1. No need to define delegate methods of UITabBar
2. No need to write code in each UIViewController

回答2:

Step 1

Assuming that you have built a tab bar that way, make sure it's the delegate to your ViewController.

Step 2

In your ViewController.swift use the following code:

import UIKit

class ViewController: UIViewController, UITabBarDelegate {

    @IBOutlet weak var tabBar: UITabBar!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        setGradientBackground(colorOne: .blue, colorTwo: .red)
    }

    func setGradientBackground(colorOne: UIColor, colorTwo: UIColor)  {
        let gradientlayer = CAGradientLayer()
        gradientlayer.frame = tabBar.bounds
        gradientlayer.colors = [colorOne.cgColor, colorTwo.cgColor]
        gradientlayer.locations = [0, 1]
        gradientlayer.startPoint = CGPoint(x: 1.0, y: 0.0)
        gradientlayer.endPoint = CGPoint(x: 0.0, y: 0.0)

        self.tabBar.layer.insertSublayer(gradientlayer, at: 0)

    }
}

Result

来源：https://stackoverflow.com/questions/55996666/how-to-apply-a-gradient-on-a-ui-tab-bar-in-swift