objective-c - iOS在部分 View 中绘制渐变

我创建了一个自定义进度栏，该进度栏继承了UIView并实现了drawRect。我设法在整个视图上绘制一个渐变。但是，我想绘制几个不同的渐变，每个渐变都位于不同的位置。如何在我的视图中将CGContextDrawLinearGradient限制为较小的rect？

glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);
CGPoint topCenter = CGPointMake(start + (CGRectGetMidX(currentBounds)/currentBounds.size.width), 0.0f);`
        CGPoint midCenter = CGPointMake(start + (CGRectGetMidX(currentBounds)/currentBounds.size.width), currentBounds.size.height);
        CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, 0);
        start = start + (values[i] / currentBounds.size.width);
        CGGradientRelease(glossGradient);
    }

最佳答案

您可以使用CGContectClipToRect限制绘图区域

然后对每个渐变执行以下操作:

CGContextSaveGState(currentContext);
CGContextClipToRect(theRect); // theRect should be the area where you want to draw the gradient
... // gradient drawing code
CGContextRestoreGState(currentContext);