title: label is not visible in UIToolBar
body: <p>I am attempting to set a label into a subclassed UIToolBar.  I am first creating the label, then converting it to a UIBarButtonItem and setting them to the toolbar, but the toolbar just appears blank. </p>
  
  <p>here is my code in my init method of my subclassed toolbar</p>
  
  <pre><code>NSMutableArray *items = [[NSMutableArray alloc] init];
  
  // prep the total label
  _totalLabel = [[UILabel alloc] init];
  _totalLabel.font = [_totalLabel.font fontWithSize:15];
  _totalLabel.textColor = [UIColor whiteColor];
  _totalLabel.text = NSLocalizedString(@"TOTAL", nil);
  _totalLabel.frame = CGRectMake(0, 0, 100, 44);
  _totalLabel.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleTopMargin;
  _totalLabel.layer.borderWidth = 2;
  _totalLabel.layer.borderColor = [UIColor greenColor].CGColor;
  _totalLabel.backgroundColor = [UIColor clearColor];
  
  UIBarButtonItem *spacer2 = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
  [items addObject:spacer2];
  
  UIBarButtonItem *total = [[UIBarButtonItem alloc] initWithCustomView:_totalLabel];
  [items addObject:total];
  
  [self setItems:items];
  </code></pre>
  
  <p>any idea whats wrong?</p>