ios - 圆角渐变 UIButton iOS

Question

您好，我想创建一个类似于(附加)图像的按钮。

这里的挑战是带有渐变颜色的圆角。我能够使用

创建圆角

view.layer setCornerRadius:radius;view.layer setMasksToBounds:YES;

我也可以创建单一的边框颜色

view.layer.borderColor = color.CGColor; view.layer.borderWidth = 宽度;

但是渐变边框颜色需要做什么呢？

我做了以下操作，但不是我想要的。我关注了这篇文章，但它没有为我提供渐变边框颜色。 UIButton w/ gradient, rounded corners, border, and drop shadow

任何人都可以帮助我理解，我如何为 UIButton 绘制渐变边框。伪代码/示例将非常有帮助。

Answer 1

这通过创建一个在中间有一个孔的多边形圆形矩形，然后使用它来剪切线性渐变的填充，将线性渐变应用于圆形矩形周围的线条。

class DisplayView : UIView {
    override func drawRect(var rect: CGRect) {
        let context = UIGraphicsGetCurrentContext()

        CGContextSaveGState(context)

        // Inset the rect so we can stroke it and not be outside the button bounds
        rect = CGRectInset(rect, 4.0, 4.0)

        // Construct the the bounds
        var path = CGPathCreateWithRoundedRect(rect, rect.size.height / 2, rect.size.height / 2, nil)

        // Fill the middle with white (or other background color
        CGContextAddPath(context, path)
        CGContextSetFillColorWithColor(context, UIColor.whiteColor().CGColor)
        CGContextFillPath(context)

        // stroke the path
        path = CGPathCreateCopyByStrokingPath(path, nil, 4.0, kCGLineCapButt, kCGLineJoinBevel, 0)

        // Add the outer edge of the button frame
        CGContextAddPath(context, path)

        // Create a gradient from white to red
        let colors = [
            UIColor.yellowColor().CGColor,
            UIColor.redColor().CGColor
        ]

        // Set the round rect as the clip
        CGContextClip(context)

        // Fill the path with the radial gradient
        let baseSpace = CGColorSpaceCreateDeviceRGB();
        let gradient = CGGradientCreateWithColors(baseSpace, colors, nil);

        CGContextDrawLinearGradient(
            context,
            gradient,
            CGPoint(x:0, y:0),
            CGPoint(x:CGRectGetMaxX(rect), y:CGRectGetMaxY(rect)),
            .allZeros)

        // Fill the line
        CGContextFillPath(context)

        CGContextRestoreGState(context)
    }
}

swift 4

class DisplayView : UIView {
    override func draw(_ rect: CGRect) {
        var rect = rect
        let context = UIGraphicsGetCurrentContext()

        context!.saveGState()

        // Inset the rect so we can stroke it and not be outside the button bounds
        rect = rect.insetBy(dx: 4.0, dy: 4.0)

        // Construct the the bounds
        var path = CGPath(roundedRect: rect,
                          cornerWidth: rect.size.width / 2,
                          cornerHeight: rect.size.height / 2,
                          transform: nil)

        // Fill the middle with white (or other background color
        context!.addPath(path)
        context?.setFillColor(UIColor.clear.cgColor)
        context?.fillPath()

        // stroke the path
        path = path.copy(strokingWithWidth: 4.0,
                         lineCap: CGLineCap.butt,
                         lineJoin: CGLineJoin.bevel,
                         miterLimit: 0)

        // Add the outer edge of the button frame
        context?.addPath(path)

        // Create a gradient from white to red
        let colors = [
            UIColor.yellow.cgColor,
            UIColor.red.cgColor
        ]

        // Set the round rect as the clip
        context?.clip()

        // Fill the path with the radial gradient
        let baseSpace = CGColorSpaceCreateDeviceRGB();
        let gradient = CGGradient(colorsSpace: baseSpace,
                                  colors: colors as CFArray,
                                  locations: nil);

        context?.drawLinearGradient(gradient!,
                                    start: CGPoint(x:0, y:0),
                                    end: CGPoint(x: rect.maxX, y: rect.maxY),
                                    options: CGGradientDrawingOptions())

        // Fill the line
        context?.fillPath()

        context?.restoreGState()
    }
}