如何为我的 iOS 导航栏创建水平渐变背景？

Question

我知道如何设置导航栏背景颜色（使用 barTintColor），但现在我正在开发一个需要水平渐变（不是典型的垂直渐变）的 iOS 应用。

如何创建水平渐变背景的导航栏？

Answer 1

你可以使用那个：

[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"gardientImage"] forBarMetrics:UIBarMetricsDefault];

for ios7导航栏高度为64px

Answer 2

如果您想以编程方式设置给定 UINavigationBar 的渐变，我有适合您的解决方案。

首先使用您想要的颜色和位置设置 CAGradientLayer。

CAGradientLayer *gradientLayer = [CAGradientLayer layer];
gradientLayer.frame = navigationBar.bounds;
gradientLayer.colors = @[ (__bridge id)[UIColor greenColor].CGColor,
                          (__bridge id)[UIColor blueColor].CGColor ];
gradientLayer.startPoint = CGPointMake(0.0, 0.5);
gradientLayer.endPoint = CGPointMake(1.0, 0.5);

然后抓取该图层的 UImage。

UIGraphicsBeginImageContext(gradientLayer.bounds.size);
[gradientLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *gradientImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

将 gradientImage 设置为 UINavigationBar 的背景图片。

[navigationBar setBackgroundImage:gradientImage forBarMetrics:UIBarMetricsDefault];

Swift解法：

[![// Setup the gradient
let gradientLayer = CAGradientLayer()
gradientLayer.frame = navigationBar.bounds
gradientLayer.colors = [UIColor.green.cgColor, UIColor.blue.cgColor]
gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.5)
gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5)

// Render the gradient to UIImage
UIGraphicsBeginImageContext(gradientLayer.bounds.size)
gradientLayer.render(in: UIGraphicsGetCurrentContext()!)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

 Set the UIImage as background property
navigationBar.setBackgroundImage(image, for: UIBarMetrics.default)

Answer 3

更新了@JulianM 对 iOS 10 / swift 3.0 的回答：

let gradientLayer = CAGradientLayer()
var updatedFrame = self.navigationController!.navigationBar.bounds
updatedFrame.size.height += 20
gradientLayer.frame = updatedFrame
gradientLayer.colors = [UIColor.green.cgColor, UIColor.blue.cgColor]
gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.5)
gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5)

UIGraphicsBeginImageContext(gradientLayer.bounds.size)
gradientLayer.render(in: UIGraphicsGetCurrentContext()!)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

self.navigationController!.navigationBar.setBackgroundImage(image, for: UIBarMetrics.default)

Answer 4

Swift

在全局中添加此功能class

func setHorizontalGradientColor(view: UIView) {
    let gradientLayer = CAGradientLayer()
    var updatedFrame = view.bounds
    updatedFrame.size.height += 20
    gradientLayer.frame = updatedFrame
    gradientLayer.colors = [UIColor.black.cgColor, UIColor.blue.cgColor]
    gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.5)
    gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5)
    view.layer.insertSublayer(gradientLayer, at: 0)
}

在任何地方使用：

setHorizontalGradientColor(view: self.bgView)

如何为我的 iOS 导航栏创建水平渐变背景？

How can I create a horizontal gradient background for my iOS nav bar?

objective-c

ios

rubymotion

ios7

ios8