如何制作 UIView 的渐变边框？
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【中文标题】如何制作 UIView 的渐变边框？【英文标题】：how to make a gradient border of UIView? 【发布时间】：2013-03-04 03:12:52 【问题描述】：我想做一个如下图的渐变边框：
但我不知道它到底是怎么做的，即我应该使用什么渐变颜色来做到这一点？如何设置我的视图以显示像图像一样的边框？
我正在使用以下代码来获取边框：
self.view.layer.borderColor = [UIColor orangeColor].CGColor;
self.view.layer.borderWidth = 2.0f;
【问题讨论】：
见***.com/questions/10200814/… 【参考方案1】：这就是我所做的，而且效果很好
extension CALayer
func addGradienBorder(colors:[UIColor],width:CGFloat = 1)
let gradientLayer = CAGradientLayer()
gradientLayer.frame = CGRect(origin: CGPointZero, size: self.bounds.size)
gradientLayer.startPoint = CGPointMake(0.0, 0.5)
gradientLayer.endPoint = CGPointMake(1.0, 0.5)
gradientLayer.colors = colors.map($0.CGColor)
let shapeLayer = CAShapeLayer()
shapeLayer.lineWidth = width
shapeLayer.path = UIBezierPath(rect: self.bounds).CGPath
shapeLayer.fillColor = nil
shapeLayer.strokeColor = UIColor.blackColor().CGColor
gradientLayer.mask = shapeLayer
self.addSublayer(gradientLayer)
【讨论】：
我注意到颜色参数是一个 UIColor 数组，但默认值是一个 CGColor 数组。不过答案很好:) 嗯，这已经过时了【参考方案2】：感谢 Tiago Mendes 的回答。
我改进了功能：
添加圆角半径。并修复了一些问题以确保正确的遮罩和给定的边框宽度：
改进的渐变层框架； 改进的蒙版路径圆角矩形。斯威夫特 5
public extension UIView
private static let kLayerNameGradientBorder = "GradientBorderLayer"
func gradientBorder(width: CGFloat,
colors: [UIColor],
startPoint: CGPoint = CGPoint(x: 0.5, y: 0.0),
endPoint: CGPoint = CGPoint(x: 0.5, y: 1.0),
andRoundCornersWithRadius cornerRadius: CGFloat = 0)
let existingBorder = gradientBorderLayer()
let border = existingBorder ?? CAGradientLayer()
border.frame = CGRect(x: bounds.origin.x, y: bounds.origin.y,
width: bounds.size.width + width, height: bounds.size.height + width)
border.colors = colors.map return $0.cgColor
border.startPoint = startPoint
border.endPoint = endPoint
let mask = CAShapeLayer()
let maskRect = CGRect(x: bounds.origin.x + width/2, y: bounds.origin.y + width/2,
width: bounds.size.width - width, height: bounds.size.height - width)
mask.path = UIBezierPath(roundedRect: maskRect, cornerRadius: cornerRadius).cgPath
mask.fillColor = UIColor.clear.cgColor
mask.strokeColor = UIColor.white.cgColor
mask.lineWidth = width
border.mask = mask
let exists = (existingBorder != nil)
if !exists
layer.addSublayer(border)
private func gradientBorderLayer() -> CAGradientLayer?
let borderLayers = layer.sublayers?.filter return $0.name == UIView.kLayerNameGradientBorder
if borderLayers?.count ?? 0 > 1
fatalError()
return borderLayers?.first as? CAGradientLayer
对于渐变层的startPoint 和endPoint 的更易读声明，我使用以下代码：
public extension CGPoint
enum CoordinateSide
case topLeft, top, topRight, right, bottomRight, bottom, bottomLeft, left
static func unitCoordinate(_ side: CoordinateSide) -> CGPoint
switch side
case .topLeft: return CGPoint(x: 0.0, y: 0.0)
case .top: return CGPoint(x: 0.5, y: 0.0)
case .topRight: return CGPoint(x: 1.0, y: 0.0)
case .right: return CGPoint(x: 0.0, y: 0.5)
case .bottomRight: return CGPoint(x: 1.0, y: 1.0)
case .bottom: return CGPoint(x: 0.5, y: 1.0)
case .bottomLeft: return CGPoint(x: 0.0, y: 1.0)
case .left: return CGPoint(x: 1.0, y: 0.5)
所以最终的用法是：
view.gradientBorder(width: 3, colors: [.red, .orange], startPoint: .unitCoordinate(.top), endPoint: .unitCoordinate(.bottom), andRoundCornersWithRadius: 12)
【讨论】：
太棒了！谢谢你。它允许我为屏幕制作边框并修复 iphone x 的半径角。 +1 ！ 对于出色的解决方案，只需为 iPhone X 系列 +1 设置圆角半径 40 很高兴为您提供帮助！实际上，如果你想要 iphone X 系列屏幕的圆角半径，你应该看看另一种绘制贝塞尔路径的方法 - apple.stackexchange.com/questions/313713/… 如何使 UIButton 工作？理想情况下，它应该适用于 UIView 的任何子类，但不适用于 UIButton。我只是在左上角看到一个点。 @eli7ah 非常酷！赞成。问题：我们如何扩展它以支持外部边界？ （向外而不是向内增长的边界）【参考方案3】：你可以使用这个来制作视图的渐变边框和圆角半径（如果你愿意的话）——
self.yourView.layer.cornerRadius=4;
self.yourView.layer.masksToBounds=YES;
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = self.yourView.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor colorWithRed:255/255.0 green:226/255.0 blue:138/255.0 alpha:1.0] CGColor], (id)[[UIColor colorWithRed:255/255.0 green:198/255.0 blue:91/255.0 alpha:0.9] CGColor],(id)[[UIColor colorWithRed:255/255.0 green:226/255.0 blue:138/255.0 alpha:1.0] CGColor], nil];
gradient.startPoint = CGPointMake(0.0, 0.0);
gradient.endPoint = CGPointMake(1, 1);
CAShapeLayer *shapeLayer =[[CAShapeLayer alloc] init];
shapeLayer.lineWidth = 15; // higher number higher border width
shapeLayer.path = [UIBezierPath bezierPathWithRect:self.yourView.bounds].CGPath;
shapeLayer.fillColor = nil;
shapeLayer.strokeColor = [UIColor blackColor].CGColor;
gradient.mask = shapeLayer;
[self.yourView.layer insertSublayer:gradient atIndex:0];
这将对您有所帮助！谢谢
【讨论】：
这个解决方案几乎对我有用，但是在圆角处边框被切断了。知道如何确保边框绕过角落吗？ 使用方法[UIBezierPath bezierPathWithRoundedRect:self.layer.bounds cornerRadius:<radius>].CGPath得到它我将它设置为UIView上的类扩展方法，因此self.layer.bounds。【参考方案4】：
这是另一个适用于 swift 4 的解决方案
import UIKit
public extension UIView
private static let kLayerNameGradientBorder = "GradientBorderLayer"
func setGradientBorder(
width: CGFloat,
colors: [UIColor],
startPoint: CGPoint = CGPoint(x: 0.5, y: 0),
endPoint: CGPoint = CGPoint(x: 0.5, y: 1)
)
let existedBorder = gradientBorderLayer()
let border = existedBorder ?? CAGradientLayer()
border.frame = bounds
border.colors = colors.map return $0.cgColor
border.startPoint = startPoint
border.endPoint = endPoint
let mask = CAShapeLayer()
mask.path = UIBezierPath(roundedRect: bounds, cornerRadius: 0).cgPath
mask.fillColor = UIColor.clear.cgColor
mask.strokeColor = UIColor.white.cgColor
mask.lineWidth = width
border.mask = mask
let exists = existedBorder != nil
if !exists
layer.addSublayer(border)
private func gradientBorderLayer() -> CAGradientLayer?
let borderLayers = layer.sublayers?.filter return $0.name == UIView.kLayerNameGradientBorder
if borderLayers?.count ?? 0 > 1
fatalError()
return borderLayers?.first as? CAGradientLayer
使用方法：
view.setGradientBorder(width: 10, colors: [UIColor(red: 47, green: 198, blue: 176), UIColor(red: 67, green: 210, blue: 128)])
【讨论】：
【参考方案5】：以下是使用 Core Graphics 的方法。创建一个 UIView 子类并在其drawRect: 创建一个渐变并用黑色内容矩形覆盖它：
- (void)drawRect:(CGRect)rect
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// Create and draw the gradient
UIColor *gradientColorTop = [UIColor orangeColor];
UIColor *gradientColorBottom = [UIColor yellowColor];
NSArray *gradientColors = @[(id) gradientColorTop.CGColor, (id) gradientColorBottom.CGColor];
CGFloat locations[] = 0.1, 0.80;
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef)(gradientColors), locations);
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
UIBezierPath *gradientBorder = [UIBezierPath bezierPathWithRoundedRect:rect
byRoundingCorners:UIRectCornerAllCorners cornerRadii:CGSizeMake(10.0, 10.0)];
[gradientBorder addClip];
CGContextDrawLinearGradient(ctx, gradient, startPoint, endPoint, 0);
// Draw the inner content rectangle
UIBezierPath *contentPath = [UIBezierPath bezierPathWithRect:CGRectInset(rect, 20.0, 20.0)];
[[UIColor blackColor] setFill];
[contentPath fill];
CGGradientRelease(gradient);
CGColorSpaceRelease(colorSpace);
这将产生与您想要达到的结果相似的结果。
【讨论】：
不同方法的比较给了我们很多思考。【参考方案6】：Christos Hadjikyriacou 回答的objective-c 版本
@implementation CALayer(Border)
-(void) addGradientBorder
CAGradientLayer *gradientLayer = [[CAGradientLayer alloc] init];
gradientLayer.frame = CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height);
gradientLayer.startPoint = CGPointMake(0.0, 0.5);
gradientLayer.endPoint = CGPointMake(1.0, 0.5);
gradientLayer.colors = @[(id)[UIColor redColor].CGColor, (id)[UIColor blueColor].CGColor];
CAShapeLayer *shapeLayer =[[CAShapeLayer alloc] init];
shapeLayer.lineWidth = 0.5;
shapeLayer.path = [UIBezierPath bezierPathWithRect:self.bounds].CGPath;
shapeLayer.fillColor = nil;
shapeLayer.strokeColor = [UIColor blackColor].CGColor;
gradientLayer.mask = shapeLayer;
[self addSublayer : gradientLayer];
@end
【讨论】：
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