如何设置具有渐变颜色的 UINavigationbar？

Question

我想将 UINavigationbar backgroundColor 设置为渐变颜色，我想通过颜色数组设置它以创建渐变，理想情况下，作为 [=12 中的可访问方法=] 将其颜色更改为此渐变。

有什么建议吗？（除了手动设置图片作为导航栏的背景图片）

Answer 1

创建渐变层并将其添加为导航栏的背景。

    CAGradientLayer *gradient = [CAGradientLayer layer];
    gradient.frame = self.navigationController.navigationBar.bounds;
    gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor whiteColor] CGColor], (id)[[UIColor blackColor] CGColor], nil];
    [self.navigationController.navigationBar setBackgroundImage:[self imageFromLayer:gradient] forBarMetrics:UIBarMetricsDefault];

用于从图层创建图像。

- (UIImage *)imageFromLayer:(CALayer *)layer
{
    UIGraphicsBeginImageContext([layer frame].size);

    [layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return outputImage;
}

还有一点，github 中有一个可用的库：CRGradientNavigationBar 你也可以使用这个库。

Answer 2

在Swift3、Swift4和Swift 5:

let gradient = CAGradientLayer()
let sizeLength = UIScreen.main.bounds.size.height * 2
let defaultNavigationBarFrame = CGRect(x: 0, y: 0, width: sizeLength, height: 64)

gradient.frame = defaultNavigationBarFrame

gradient.colors = [UIColor.white.cgColor, UIColor.black.cgColor]

UINavigationBar.appearance().setBackgroundImage(self.image(fromLayer: gradient), for: .default)

从图层创建图像：

func image(fromLayer layer: CALayer) -> UIImage {
    UIGraphicsBeginImageContext(layer.frame.size)

    layer.render(in: UIGraphicsGetCurrentContext()!)

    let outputImage = UIGraphicsGetImageFromCurrentImageContext()

    UIGraphicsEndImageContext()

    return outputImage!
}

在Swift 2:

let gradient = CAGradientLayer()
let sizeLength = UIScreen.mainScreen().bounds.size.height * 2
let defaultNavigationBarFrame = CGRectMake(0, 0, sizeLength, 64)

gradient.frame = defaultNavigationBarFrame

gradient.colors = [UIColor.whiteColor().CGColor, UIColor.blackColor().CGColor]

UINavigationBar.appearance().setBackgroundImage(self.image(fromLayer: gradient), forBarMetrics: .Default)

从图层创建图像：

func image(fromLayer layer: CALayer) -> UIImage {    
    UIGraphicsBeginImageContext(layer.frame.size)

    layer.renderInContext(UIGraphicsGetCurrentContext()!)

    let outputImage = UIGraphicsGetImageFromCurrentImageContext()

     UIGraphicsEndImageContext()

    return outputImage!
}

Answer 3

在Swift3

let gradient = CAGradientLayer()
let sizeLength = UIScreen.main.bounds.size.height * 2
let defaultNavigationBarFrame = CGRect(x: 0, y: 0, width: sizeLength, height: 64)
gradient.frame = defaultNavigationBarFrame
gradient.colors = [UIColor.white.cgColor, UIColor.black.cgColor]
UINavigationBar.appearance().setBackgroundImage(self.image(fromLayer: gradient), for: .default)

func image(fromLayer layer: CALayer) -> UIImage {
    UIGraphicsBeginImageContext(layer.frame.size)
    layer.render(in: UIGraphicsGetCurrentContext()!)
    let outputImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return outputImage!
}

Answer 4

这是在 Swift 3.0 中不使用中间体 CAGradientLayer 而只使用 CoreGraphics 的解决方案。

本质上，该方法使用传递的渐变颜色动态创建一个 UIImage 并设置它。

extension UINavigationBar
{
    /// Applies a background gradient with the given colors
    func apply(gradient colors : [UIColor]) {
        var frameAndStatusBar: CGRect = self.bounds
        frameAndStatusBar.size.height += 20 // add 20 to account for the status bar

        setBackgroundImage(UINavigationBar.gradient(size: frameAndStatusBar.size, colors: colors), for: .default)
    }

    /// Creates a gradient image with the given settings
    static func gradient(size : CGSize, colors : [UIColor]) -> UIImage?
    {
        // Turn the colors into CGColors
        let cgcolors = colors.map { [=10=].cgColor }

        // Begin the graphics context
        UIGraphicsBeginImageContextWithOptions(size, true, 0.0)

        // If no context was retrieved, then it failed
        guard let context = UIGraphicsGetCurrentContext() else { return nil }

        // From now on, the context gets ended if any return happens
        defer { UIGraphicsEndImageContext() }

        // Create the Coregraphics gradient
        var locations : [CGFloat] = [0.0, 1.0]
        guard let gradient = CGGradient(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: cgcolors as NSArray as CFArray, locations: &locations) else { return nil }

        // Draw the gradient
        context.drawLinearGradient(gradient, start: CGPoint(x: 0.0, y: 0.0), end: CGPoint(x: size.width, y: 0.0), options: [])

        // Generate the image (the defer takes care of closing the context)
        return UIGraphicsGetImageFromCurrentImageContext()
    }
}

defer 声明使它比以前的版本干净得多。请注意，CGGradient 自 iOS 8.0.

起可用

此外，这会创建从左到右的渐变，调整 drawLinearGradient（start 和 end）的参数会移动位置。这取决于您的实施。

Answer 5

详情

Xcode 11.4 (11E146), swift 5
测试 iOS 13.1、12.2、11.0.1

解决方案

class UINavigationBarGradientView: UIView {

    enum Point {
        case topRight, topLeft
        case bottomRight, bottomLeft
        case custom(point: CGPoint)

        var point: CGPoint {
            switch self {
                case .topRight: return CGPoint(x: 1, y: 0)
                case .topLeft: return CGPoint(x: 0, y: 0)
                case .bottomRight: return CGPoint(x: 1, y: 1)
                case .bottomLeft: return CGPoint(x: 0, y: 1)
                case .custom(let point): return point
            }
        }
    }

    private weak var gradientLayer: CAGradientLayer!

    convenience init(colors: [UIColor], startPoint: Point = .topLeft,
                     endPoint: Point = .bottomLeft, locations: [NSNumber] = [0, 1]) {
        self.init(frame: .zero)
        let gradientLayer = CAGradientLayer()
        gradientLayer.frame = frame
        layer.addSublayer(gradientLayer)
        self.gradientLayer = gradientLayer
        set(colors: colors, startPoint: startPoint, endPoint: endPoint, locations: locations)
        backgroundColor = .clear
    }

    func set(colors: [UIColor], startPoint: Point = .topLeft,
             endPoint: Point = .bottomLeft, locations: [NSNumber] = [0, 1]) {
        gradientLayer.colors = colors.map { [=10=].cgColor }
        gradientLayer.startPoint = startPoint.point
        gradientLayer.endPoint = endPoint.point
        gradientLayer.locations = locations
    }

    func setupConstraints() {
        guard let parentView = superview else { return }
        translatesAutoresizingMaskIntoConstraints = false
        topAnchor.constraint(equalTo: parentView.topAnchor).isActive = true
        leftAnchor.constraint(equalTo: parentView.leftAnchor).isActive = true
        parentView.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
        parentView.rightAnchor.constraint(equalTo: rightAnchor).isActive = true
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        guard let gradientLayer = gradientLayer else { return }
        gradientLayer.frame = frame
        superview?.addSubview(self)
    }
}

extension UINavigationBar {
    func setGradientBackground(colors: [UIColor],
                               startPoint: UINavigationBarGradientView.Point = .topLeft,
                               endPoint: UINavigationBarGradientView.Point = .bottomLeft,
                               locations: [NSNumber] = [0, 1]) {
        guard let backgroundView = value(forKey: "backgroundView") as? UIView else { return }
        guard let gradientView = backgroundView.subviews.first(where: { [=10=] is UINavigationBarGradientView }) as? UINavigationBarGradientView else {
            let gradientView = UINavigationBarGradientView(colors: colors, startPoint: startPoint,
                                                           endPoint: endPoint, locations: locations)
            backgroundView.addSubview(gradientView)
            gradientView.setupConstraints()
            return
        }
        gradientView.set(colors: colors, startPoint: startPoint, endPoint: endPoint, locations: locations)
    }
}

用法

navigationBar.setGradientBackground(colors: [.lightGray, .red], startPoint: .topLeft, endPoint: .bottomRight)

Answer 6

Objective C 也适用于 iPhone X 的解决方案：

- (void)addGradientToNavigationBar
{
    CAGradientLayer *gradient = [CAGradientLayer layer];
    CGRect gradientFrame = self.navigationController.navigationBar.bounds;
    gradientFrame.size.height += [UIApplication sharedApplication].statusBarFrame.size.height;
    gradient.frame = gradientFrame;
    gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor colorGradientUp] CGColor], (id)[[UIColor colorGradientDown] CGColor], nil];
    [self.navigationController.navigationBar setBackgroundImage:[self imageFromLayer:gradient] forBarMetrics:UIBarMetricsDefault];
}

- (UIImage *)imageFromLayer:(CALayer *)layer
{
    UIGraphicsBeginImageContext([layer frame].size);

    [layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return outputImage;
}

Answer 7

对于Swift4.2

extension UINavigationBar {
    func setGradientBackground(colors: [Any]) {
        let gradient: CAGradientLayer = CAGradientLayer()
        gradient.locations = [0.0 , 0.5, 1.0]
        gradient.startPoint = CGPoint(x: 0.0, y: 1.0)
        gradient.endPoint = CGPoint(x: 1.0, y: 1.0)

        var updatedFrame = self.bounds
        updatedFrame.size.height += self.frame.origin.y
        gradient.frame = updatedFrame
        gradient.colors = colors;
        self.setBackgroundImage(self.image(fromLayer: gradient), for: .default)
    }

    func image(fromLayer layer: CALayer) -> UIImage {
        UIGraphicsBeginImageContext(layer.frame.size)
        layer.render(in: UIGraphicsGetCurrentContext()!)
        let outputImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return outputImage!
    }
}

使用方法

   self.navigationController?.navigationBar.setGradientBackground(colors: [
            UIColor.red.cgColor,
            UIColor.green.cgColor,
            UIColor.blue.cgColor
            ])

Answer 8

这是一个框架，用于不同的UI组件渐变包括UI导航栏： enter link description here

首先：然后在你的根 ViewController 中嵌入到 UINavigationController

import SHNDStuffs

将其放入您的 ViewDidLoad()

class RootViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        SHNDNavigationBarGradient(firstColor: .darkGray,
                                  secondColor: .white,
                                  tintColor: .black,
                                  isHorizontal: true)
}

Answer 9

SWIFT 5

要使导航栏和状态栏的水平渐变背景也一样。只需将此代码放入 viewcontroller 的 viewDidLoad() 方法中。

    self.navigationItem.title = "Gradiant Back Ground"
    let gradientLayer = CAGradientLayer()
    var updatedFrame = self.navigationController!.navigationBar.bounds
    updatedFrame.size.height += UIApplication.shared.statusBarFrame.size.height
    gradientLayer.frame = updatedFrame
    gradientLayer.colors = [UIColor.green.cgColor, UIColor.blue.cgColor] // start color and end color
    gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.0) // Horizontal gradient start
    gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.0) // Horizontal gradient end
    UIGraphicsBeginImageContext(gradientLayer.bounds.size)
    gradientLayer.render(in: UIGraphicsGetCurrentContext()!)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    self.navigationController!.navigationBar.setBackgroundImage(image, for: UIBarMetrics.default)

输出渐变看起来像这样。

Answer 10

Swift 5

在渐变中包含状态栏。
不使用图像。
使用透明度，以便通过导航栏可以看到内容。

extension UINavigationBar {

    func addGradient(_ toAlpha: CGFloat, _ color: UIColor) {
        let gradient = CAGradientLayer()
        gradient.colors = [
            color.withAlphaComponent(toAlpha).cgColor,
            color.withAlphaComponent(toAlpha).cgColor,
            color.withAlphaComponent(0).cgColor
        ]
        gradient.locations = [0, 0.8, 1]
        var frame = bounds
        frame.size.height += UIApplication.shared.statusBarFrame.size.height
        frame.origin.y -= UIApplication.shared.statusBarFrame.size.height
        gradient.frame = frame
        layer.insertSublayer(gradient, at: 1)
    }

}

Answer 11

这个来自 Lawrence Tan  的精彩教程展示了如何使用 barTintColor 而不使用 backgroundImage 设置渐变：https://medium.com/swift2go/add-gradient-to-navigation-bar-in-swift-9284fe91fea2

总结

CAGradientLayer 分机

extension CAGradientLayer {

    class func primaryGradient(on view: UIView) -> UIImage? {
        let gradient = CAGradientLayer()
        let flareRed = UIColor(displayP3Red: 241.0/255.0, green: 39.0/255.0, blue: 17.0/255.0, alpha: 1.0)
        let flareOrange = UIColor(displayP3Red: 245.0/255.0, green: 175.0/255.0, blue: 25.0/255.0, alpha: 1.0)
        var bounds = view.bounds
        bounds.size.height += UIApplication.shared.statusBarFrame.size.height
        gradient.frame = bounds
        gradient.colors = [flareRed.cgColor, flareOrange.cgColor]
        gradient.startPoint = CGPoint(x: 0, y: 0)
        gradient.endPoint = CGPoint(x: 1, y: 0)
        return gradient.createGradientImage(on: view)
    }

    private func createGradientImage(on view: UIView) -> UIImage? {
        var gradientImage: UIImage?
        UIGraphicsBeginImageContext(view.frame.size)
        if let context = UIGraphicsGetCurrentContext() {
            render(in: context)
            gradientImage = UIGraphicsGetImageFromCurrentImageContext()?.resizableImage(withCapInsets: UIEdgeInsets.zero, resizingMode: .stretch)
        }
        UIGraphicsEndImageContext()
        return gradientImage
    }
}

应用渐变

guard
    let navigationController = navigationController,
    let flareGradientImage = CAGradientLayer.primaryGradient(on: navigationController.navigationBar)
    else {
        print("Error creating gradient color!")
        return
    }

navigationController.navigationBar.barTintColor = UIColor(patternImage: flareGradientImage)

如何设置具有渐变颜色的 UINavigationbar？

How can I set the UINavigationbar with gradient color?

core-graphics

uinavigationbar

ios

详情

解决方案

用法

Swift 5

总结