UIBarButtonItem

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  property
•    action  property
•    style  property
•    possibleTitles  property
•    width  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0
•    customView  property

Customizing 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: