Question

I am adding a UILabel instance as a subview of my custom UITableViewCell instance’s contentView.

When I select the cell, the row is highlighted blue, except for the background of the label. The label text is sharp.

When I set the label and content view backgroundColor property to [UIColor clearColor], the label text becomes blurry.

How do I set the label background color to be clear, to allow the row highlight to come through, while still keeping the label text sharp?

One suggestion I read elsewhere was to round the label’s frame values, but this did not have any effect.

CODE

Here is a snippet of my custom UITableViewCell subview’s -setNeedsLayout method:

UILabel *_objectTitleLabel = [[UILabel alloc] initWithFrame:CGRectNull];
_objectTitleLabel.text = [self.awsObject cleanedKey];
_objectTitleLabel.font = [UIAppDelegate defaultObjectLabelFont];
_objectTitleLabel.highlightedTextColor = [UIColor clearColor]; //[UIAppDelegate defaultLabelShadowTint];
_objectTitleLabel.backgroundColor = [UIColor clearColor]; //[UIAppDelegate defaultWidgetBackgroundTint];
_objectTitleLabel.frame = CGRectMake(
        kCellImageViewWidth + 2.0 * self.indentationWidth,
        0.5 * (self.tableView.rowHeight - 1.5 * kCellLabelHeight) + kCellTitleYPositionNudge,
        contentViewWidth,
        kCellLabelHeight
);
_objectTitleLabel.frame = CGRectIntegral(_objectTitleLabel.frame);
_objectTitleLabel.tag = kObjectTableViewCellTitleSubviewType;
//NSLog(@"_objectTitleLabel: %@", NSStringFromCGRect(_objectTitleLabel.frame));
[self.contentView addSubview:_objectTitleLabel];
[_objectTitleLabel release], _objectTitleLabel = nil;

...

self.contentView.backgroundColor = [UIAppDelegate defaultWidgetBackgroundTint]; 
self.contentView.clearsContextBeforeDrawing = YES;
self.contentView.autoresizesSubviews = YES;
self.contentView.clipsToBounds = YES;
self.contentView.contentMode = UIViewContentModeRedraw;

Answer 1

The issue is sub-pixel rendering, which occurs when your origin (which is a float value) has a non-zero fractional component. Round to the nearest whole number and you should be fine.