A custom bar button item displayed on the left (or leading) edge of the navigation bar when the receiver is the top navigation item.
- iOS 2.0+
- tvOS 9.0+
The contents of this property always refer to the first bar button item in the
left array. Assigning a new value to this property replaces the first item in the
left array with the new value. Setting this property to
nil removes the first item in the array. If the bar button item is already in the array, it is moved from its current location to the front of the array.
In a right-to-left user interface, the position of the left bar button item is automatically flipped.