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copied!<p>To paint a <code>MKPolyline</code> with a gradient, you can use a custom subclass of <code>MKPolylineView</code>. As CoreGraphics does not support stroking a path with a gradient, we have to </p> <ol> <li>convert the path to a shape that traces the paths edge using <code>CGPathCreateCopyByStrokingPath</code></li> <li>clip the context to that shape</li> <li>fill using <code>CGContextDrawLinearGradient</code></li> </ol> <p>Here is a subclass to get you started:</p> <pre><code>@interface TWOGradientPolylineView : MKPolylineView @end @implementation TWOGradientPolylineView - (void)strokePath:(CGPathRef)path inContext:(CGContextRef)context { CGFloat lineWidth = CGContextConvertSizeToUserSpace(context, (CGSize){self.lineWidth, self.lineWidth}).width; CGPathRef pathToFill = CGPathCreateCopyByStrokingPath(path, NULL, lineWidth, self.lineCap, self.lineJoin, self.miterLimit); CGRect rect = CGPathGetBoundingBox(pathToFill); CGContextAddPath(context, pathToFill); CGPathRelease(pathToFill); CGContextClip(context); CGFloat gradientLocations[2] = {0.0f, 1.0f}; CGFloat gradientColors[8] = {1.0f, 0.0f, 0.0f, 0.75f, 1.0f, 1.0f, 0.0f, 0.75f}; CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGGradientRef gradient = CGGradientCreateWithColorComponents(colorSpace, gradientColors, gradientLocations, 2); CGColorSpaceRelease(colorSpace); CGPoint gradientStart = rect.origin; CGPoint gradientEnd = {CGRectGetMaxX(rect), CGRectGetMaxY(rect)}; CGContextDrawLinearGradient(context, gradient, gradientStart, gradientEnd, kCGGradientDrawsAfterEndLocation); CGGradientRelease(gradient); } @end </code></pre> <p>Here is a screenshot of a path drawn with the class above:</p> <p><img src="https://i.stack.imgur.com/XrxJl.png" alt="screenshot of a path with a gradient"></p>

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