A grey UIBarButtonItem.

On iOS 5 & 6, it turns out that assigning a pure greyscale color to a ‘plain’ style UIBarButtonItem’s tintColor, such as those returned by +[UIColor lightGrayColor], +[UIColor grayColor], and +[UIColor darkGrayColor], will not work as you might expect.

What happens instead is that the icon becomes white. To remedy this, simply define a color with more channels, like so:

[UIColor colorWithRed:0.63 green:0.65 blue:0.62 alpha:1];