一个bar button item是专门用来放在uitoolbar 和uinavigationbar上的对象。他继承自UIBarItem。UIBarButtonItem定义了额外的初始化方法和属性用于再toolbars喝navigation bars上。
Initializing an Item
– initWithBarButtonSystemItem:target:action:– initWithCustomView:– initWithImage:style:target:action:– initWithTitle:style:target:action:– initWithImage:landscapeImagePhone:style:target:action:Getting and Setting Properties
target propertyaction propertystyle propertypossibleTitles propertywidth property 如果此值为正的，宽度固定，为0或负数，按照标题、图像大小来定宽度。默认为0customView propertyCustomizing Appearance
tintColor property– backButtonBackgroundImageForState:barMetrics:– setBackButtonBackgroundImage:forState:barMetrics:– backButtonTitlePositionAdjustmentForBarMetrics:– setBackButtonTitlePositionAdjustment:forBarMetrics:– backButtonBackgroundVerticalPositionAdjustmentForBarMetrics:– setBackButtonBackgroundVerticalPositionAdjustment:forBarMetrics:– backgroundVerticalPositionAdjustmentForBarMetrics:– setBackgroundVerticalPositionAdjustment:forBarMetrics:– backgroundImageForState:barMetrics:– setBackgroundImage:forState:barMetrics:– backgroundImageForState:style:barMetrics:– setBackgroundImage:forState:style:barMetrics:– titlePositionAdjustmentForBarMetrics:– setTitlePositionAdjustment:forBarMetrics:
UIBarButtonItem,布布扣,bubuko.com
原文：http://www.cnblogs.com/honeblog/p/3860294.html