在UIScrollView中覆盖drawRect时的黑色背景

问题描述

所以我试图在我的UIScrolLView中覆盖drawRect，但它给了我这个黑色背景而不是我为UIScrollView指定的背景颜色。为什么是这样？如果我删除了drawRect代码，那么一切都很好：

So I am trying to override drawRect in my UIScrolLView, however it gives me this black background instead of the background color that I've specified for my UIScrollView. Why is this? If I remove the drawRect code then everything is fine:

- (void)drawRect:(CGRect)rect
{
    [super drawRect:rect];
    if (shouldDrawVerticalLineForProfile){

        CGContextRef context = UIGraphicsGetCurrentContext();
        CGColorRef separatorColor = [UIColor colorWithRed:47.0/255.0 green:47.0/255.0 
                                                     blue:47.0/255.0 alpha:1.0].CGColor;

        // Add at bottom
        CGPoint startPoint = CGPointMake(60, 0);
        CGPoint endPoint = CGPointMake(60, 10000);

        CGContextSaveGState(context);
        CGContextSetLineCap(context, kCGLineCapSquare);
        CGContextSetStrokeColorWithColor(context, separatorColor);
        CGContextSetLineWidth(context, 5.0);
        CGContextMoveToPoint(context, startPoint.x + 0.5, startPoint.y + 0.5);
        CGContextAddLineToPoint(context, endPoint.x + 0.5, endPoint.y + 0.5);
        CGContextStrokePath(context);
        CGContextRestoreGState(context);  

    }

}

推荐答案

我猜你要搜索的是：

myScrollViewInstance.opaque = NO

之后滚动视图的背景不再是黑色。

After that the background of your scroll view should not be black anymore.

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