Can't draw in UITableViewCell's drawRect

问题

I'm having trouble drawing in the drawRect method of my custom UITableViewCell. Here is the code I am using

- (void)drawRect:(CGRect)rect
{
    CGContextRef ctx  = UIGraphicsGetCurrentContext();
    CGPoint origin    = _faceView.frame.origin;
    CGFloat width     = _faceView.frame.size.width;
    CGFloat height    = _faceView.frame.size.height;
    CGFloat border    = 2.0f;


    CGPoint startPt   = CGPointMake(origin.x + width/2, self.frame.size.height);
    CGContextBeginPath(ctx);
    CGContextMoveToPoint(ctx, startPt.x, startPt.y);

    CGPoint basePt    = CGPointMake(startPt.x, origin.y - height - border);
    CGContextAddLineToPoint(ctx, basePt.x, basePt.y);

    CGRect circleRect = CGRectMake(origin.x - border, origin.y - border, width + 2 * border, height + 2 * border);
    CGContextAddEllipseInRect(ctx, circleRect);

    UIColor *color = [UIColor redColor];
    CGContextSetFillColorWithColor(ctx, color.CGColor);
    CGContextSetStrokeColorWithColor(ctx, color.CGColor);
    CGContextSetLineWidth(ctx, 1.0f);

    CGContextDrawPath(ctx, kCGPathFillStroke);
}

I've debugged to make sure that all of the numeric values make sense and it appears that they do. Can't really find out why nothing is being drawn on screen.

For what its worth, this is a cell defined in a nib as well. And i'm building with the iOS 7 sdk.

Any ideas?

tahnks

回答1:

You probably shouldn't do this in UITableViewCell's own drawRect. Instead, create a custom UIView and add it as a subview.

See also this answer.

回答2:

Try set backgroungcolor property to transparent color

self.backgroundColor = [UIColor clearColor]

回答3:

You have to set

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
       .....
       [cell setNeedsDisplay];
       return cell;
}

回答4:

Try set backgroundColor of contentView property to clear color

self.contentView = [UIColor clearColor];

来源：https://stackoverflow.com/questions/18883975/cant-draw-in-uitableviewcells-drawrect