如何为我的 iOS 导航栏创建水平渐变背景？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/31889600/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How can I create a horizontal gradient background for my iOS nav bar?
提问by Andrew
I know how to set a navigation bar background color (with barTintColor), but now I am working on an iOS app that calls for a horizontal gradient (not the typical vertical gradient).
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 应用程序。
How can I create a navigation bar with a horizontal gradient background?
如何创建具有水平渐变背景的导航栏？
回答by JulianM
If you want to programmatically set the gradient of a given UINavigationBar I have a solution for you.
如果您想以编程方式设置给定 UINavigationBar 的渐变，我为您提供了一个解决方案。
First setup a CAGradientLayerwith your desired colors and locations.
首先设置一个CAGradientLayer你想要的颜色和位置。
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);
Then grab the UImage for that layer.
然后获取该层的 UImage。
UIGraphicsBeginImageContext(gradientLayer.bounds.size);
[gradientLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *gradientImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Set the gradientImageas the backgroundImage for your UINavigationBar.
将 设置gradientImage为您的UINavigationBar.
[navigationBar setBackgroundImage:gradientImage forBarMetrics:UIBarMetricsDefault];
Swift Solution:
迅捷解决方案：
[![// 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)
回答by Makalele
Updated @JulianM answer for iOS 10 / swift 3.0:
更新了 iOS 10 / swift 3.0 的 @JulianM 答案：
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)
回答by Rohit suvagiya
You can use that :
你可以使用它：
[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"gardientImage"] forBarMetrics:UIBarMetricsDefault];
for ios 7 navigation bar height is 64px
ios 7 导航栏高度为 64px
