如何在 iOS 中用渐变填充由 CGPoints 定义的形状？

我在代码中设置了自定义形状的箭头。我想做的就是用渐变填充它。问题是，我不知道如何用渐变填充非矩形形状（暗框内的空间）。有任何想法吗？

 //Define colours used in drawing
CGContextRef context = UIGraphicsGetCurrentContext();

CGColorRef lightColor = _lightColor.CGColor;
CGColorRef darkColor = _darkColor.CGColor;
CGColorRef shadowColor = [UIColor colorWithRed:0.2 green:0.2 
                                          blue:0.2 alpha:0.5].CGColor;   

//Get label text size to help determine sizes for drawing
CGSize textSize = [[_titleLabel text] sizeWithFont:[_titleLabel font]];

//Set shadow
CGContextSaveGState(context);
CGContextSetShadowWithColor(context, CGSizeMake(0, 2), 3.0, shadowColor);

//Set arrow shape
CGPoint rectangle_points[] =
{
    CGPointMake(_coloredBoxRect.origin.x, _coloredBoxRect.origin.y),
    CGPointMake(textSize.width+10, _coloredBoxRect.origin.y),
    CGPointMake(textSize.width+40, _coloredBoxRect.origin.y+20),
    CGPointMake(textSize.width+10, _coloredBoxRect.origin.y+40),
    CGPointMake(_coloredBoxRect.origin.x, _coloredBoxRect.origin.y+40),
    CGPointMake(_coloredBoxRect.origin.x, _coloredBoxRect.origin.y),
};
CGContextAddLines(context, rectangle_points, 6);    
CGContextSetFillColorWithColor(context, lightColor);
CGContextFillPath(context);

CGContextRestoreGState(context);

//Draw dark frame for the arrow
CGContextSetStrokeColorWithColor(context, darkColor);
CGContextSetLineWidth(context, 1.0);  
CGContextSaveGState(context);
draw1PxStroke(context, CGPointMake(_coloredBoxRect.origin.x, _coloredBoxRect.origin.y), CGPointMake(textSize.width+10, _coloredBoxRect.origin.y), darkColor);
draw1PxStroke(context, CGPointMake(textSize.width+10, _coloredBoxRect.origin.y+40), CGPointMake(_coloredBoxRect.origin.x, _coloredBoxRect.origin.y+40), darkColor);
draw1PxStroke(context, CGPointMake(_coloredBoxRect.origin.x, _coloredBoxRect.origin.y), CGPointMake(_coloredBoxRect.origin.x, _coloredBoxRect.origin.y+40), darkColor);
draw1PxStroke(context, CGPointMake(textSize.width+10, _coloredBoxRect.origin.y), CGPointMake(textSize.width+40, _coloredBoxRect.origin.y+20), darkColor);
draw1PxStroke(context, CGPointMake(textSize.width+10, _coloredBoxRect.origin.y+40), CGPointMake(textSize.width+40, _coloredBoxRect.origin.y+20), darkColor);    
CGContextRestoreGState(context);

查看这个苹果示例应用程序。 它正是您在“多边形”部分中所需要的（用于填充多边形）。 您需要更改的是绘制渐变而不是像示例中那样绘制。 示例中的“渐变”部分还举例说明了绘制渐变。

http://developer.apple.com/library/ios/#samplecode/QuartzDemo/Introduction/Intro.html http://developer.apple.com/library/ios/#samplecode/QuartzDemo/Introduction/Intro.html

希望这可以帮助， 弗拉德