如何调整导航条上的leftBarButtonItem和rightBarButtonItem的位置

      最近发现一些开发ios的新朋友在碰到调整导航条上leftBarButtonItem和rightBarButtonItem的位置的问题显得非常棘手 , 我上网查了下发现网上对这种问题的回答或者提出的解决方案并不是很好，而且很多的都是根本就无法达到自由调整左右按钮位置的。下面我以leftBarButtonItem为例:

设想这类问题的出处：（美女的诱惑）

自定义leftBarButtonItem和rightBarButtonItem 同时为了更好体现封装性新建一个分类来封装好button方法

然后我在NavigationController中来设置:

本来这样是没有什么问题的 但是如果切图的美女把leftBarButtonItem搞的有点不正常 结果就这样悲剧了：

左右不对称，这搞什么嘛 这让搞开发的情何以堪啊，当然了我们开发人员看见了还不算最差，一定不要让我的上帝(用户)看见才行。有人就说这个问题还不简单， 叫切图的那位美女重新搞搞不就行了 我直接跟你说吧 切图美女说这张图完全没问题 就是这样的，爱要不要，爱搞不搞。好吧 我表示真的有气魄，有内涵。

那么现在问题来了 在不搞切图美女不搞图片的情况下搞，搞是可以搞，但是非常难搞，说罢 ，现在就开始搞。

分类弄了就不要浪费了 重新搞下leftBarButtonItem就行

这好像就搞定了

重点：

这里需要提到BarButtonSystemItem的样式－ UIBarButtonSystemItemFixedSpace

我不多说 请看官方解释:Blank space to add between other items. Only the width property is used when this value is set.  反正我是看不懂 。再来说说negativeSpacer.width = 0 表示leftBarButtonItem的x离屏幕的左边还有15像素 同样表示rightBarButtonItem的CGRectGetMaxX()离屏幕的右边还有15像素 那么好像我们就可以通过negativeSpacer.width来调整leftBarButtonItem的位置。搞了老半天原来就是得靠这家伙。但有一点：negativeSpacer.width赋值负数对于leftBarButtonItem来说是左移多少像素 对于rightBarButtonItem来说是右移多少像素  反之亦然.

说了这么多 我只想说一句 切图的美女 你对我好点 好不好？

最后附上BarButtonSystemItem的系统样式：

typedef enum {   UIBarButtonSystemItemDone,   UIBarButtonSystemItemCancel,   UIBarButtonSystemItemEdit,   UIBarButtonSystemItemSave,   UIBarButtonSystemItemAdd,   UIBarButtonSystemItemFlexibleSpace,   UIBarButtonSystemItemFixedSpace,   UIBarButtonSystemItemCompose,   UIBarButtonSystemItemReply,   UIBarButtonSystemItemAction,   UIBarButtonSystemItemOrganize,   UIBarButtonSystemItemBookmarks,   UIBarButtonSystemItemSearch,   UIBarButtonSystemItemRefresh,   UIBarButtonSystemItemStop,   UIBarButtonSystemItemCamera,   UIBarButtonSystemItemTrash,   UIBarButtonSystemItemPlay,   UIBarButtonSystemItemPause,   UIBarButtonSystemItemRewind,   UIBarButtonSystemItemFastForward,   UIBarButtonSystemItemUndo ,        // iOS 3.0 and later   UIBarButtonSystemItemRedo ,        // iOS 3.0 and later   UIBarButtonSystemItemPageCurl ,    // iOS 4.0 and later } UIBarButtonSystemItem;

Constants

• UIBarButtonSystemItemDone

  The system Done button. Localized. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemCancel

  The system Cancel button. Localized. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemEdit

  The system Edit button. Localized. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemSave

  The system Save button. Localized. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemAdd

  The system plus button containing an icon of a plus sign. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemFlexibleSpace

  Blank space to add between other items. The space is distributed equally between the other items. Other item properties are ignored when this value is set.

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemFixedSpace

  Blank space to add between other items. Only the width property is used when this value is set.

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemCompose

  The system compose button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemReply

  The system reply button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemAction

  The system action button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemOrganize

  The system organize button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemBookmarks

  The system bookmarks button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemSearch

  The system search button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemRefresh

  The system refresh button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemStop

  The system stop button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemCamera

  The system camera button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemTrash

  The system trash button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemPlay

  The system play button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemPause

  The system pause button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemRewind

  The system rewind button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemFastForward

  The system fast forward button. 

  Available in iOS 2.0 and later.

• UIBarButtonSystemItemUndo

  The system undo button. 

  Available in iOS 3.0 and later.

• UIBarButtonSystemItemRedo

  The system redo button. 

  Available in iOS 3.0 and later.

• UIBarButtonSystemItemPageCurl

  The system page curl button. 

  This bar button image can be used only for bar button items placed on toolbars.

  Available in iOS 4.0 and later.

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