How can I remove UILabel's gray border on the right side?

Question

I have added an UILabel to a custom cell's contentView. I met with a strange side effect. On the right border there is a gray edge. I don't know why. I just added an ordinary UILabel, I have done nothing else.

UILabel *label = [[UILabel alloc] initWithFrame:CGRectZero];
label.text = @"value1";
label.textAlignment = UITextAlignmentCenter;
[self.contentView addSubview:label];

- (void)layoutSubviews
{
    UILabel *label = [self.contentView.subviews objectAtIndex:i];
    label.frame = CGRectMake(…);
}

Answer 1

I don't know the reason, but the solution is to get rid of that gray edge to set the background color of the cell to clearColor.

label.backgroundColor = [UIColor clearColor];