Strange behavior when adding colorful UIImageView to a UITableViewCell

Question

I am attaching a colorful state indicator to the left of every UITableViewCell the following way:

CGRect rect = CGRectMake(3, 1, 12, 42);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();

switch (cellState)
        {
            case State_OK:
                CGContextSetFillColorWithColor(context,
                                               [[UIColor customGreen] CGColor]);
                break;
            case State_Warning:
                CGContextSetFillColorWithColor(context,
                                               [[UIColor customYellow] CGColor]);
                break;
            case State_Critical:
                CGContextSetFillColorWithColor(context,
                                               [[UIColor customRed] CGColor]);
                break;
            case State_Unknown:
                CGContextSetFillColorWithColor(context,
                                               [[UIColor customGray] CGColor]);
                break;
        }

        CGContextFillRect(context, rect);
        UIImageView *imageView = [[UIImageView alloc] initWithImage:UIGraphicsGetImageFromCurrentImageContext()];
        imageView.alpha = 0.7;
        UIGraphicsEndImageContext();

        [cell.contentView addSubview:imageView];

return cell;

But somehow I am getting very strange colors:

When I set imageView.alpha = 1; The colors are fine again:

Adding the Images like this:

cell.imageView.image = UIGraphicsGetImageFromCurrentImageContext();
cell.imageView.alpha = 0.7;

Works just fine! Even with alpha. But I don't really want to do it that way.

Answer 1

The problem could be that the colours are blending with the background of the cell. What is the background color of the cell?

Another reason could be that your cells images are being reused, so you are setting the images on top previous images.