修复iOS7下leftBarButtonItem位置相比之前版本靠右的问题

Xcode升级到5.0版本之后，在iOS7下，通过 leftBarButtonItem 设定的左导航栏按钮会出现明显的靠右偏移的情况，就像下面图片这样：

这样的效果看起来是比较别扭的，为了让iOS7下面看起来跟以前一样，就需要针对iOS7特别处理一下了：

UIButton * backButton = [UIButton buttonWithType:UIButtonTypeCustom];
backButton.frame = CGRectMake(0, 0, 60, 44);
[backButton setImage:[UIImage imageNamed:@ "back_btn_bg.png" ] forState:UIControlStateNormal];
[backButton setTitle:@ "Back" forState:UIControlStateNormal];
[backButton setTitleEdgeInsets:UIEdgeInsetsMake(-1, -55, 0, 0)];
[backButton.titleLabel setFont:[UIFont boldSystemFontOfSize:14.0]];
[backButton setTitleColor:[UIColor colorWithRed:233.0/255.0 green:220.0/255.0 blue:207.0/255.0 alpha:1.0]
                 forState:UIControlStateNormal];
UIBarButtonItem *backNavigationItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];

// 调整 leftBarButtonItem 在 iOS7 下面的位置
if (([[[UIDevice currentDevice] systemVersion] floatValue]>=7.0?20:0)){
  UIBarButtonItem *negativeSpacer = [[UIBarButtonItem alloc]
                                     initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace
                                     target: nil action: nil ];
  negativeSpacer.width = -10;
  self .navigationItem.leftBarButtonItems = @[negativeSpacer, backNavigationItem];
} else
  self .navigationItem.leftBarButtonItem = backNavigationItem;

这样就可以了，示例程序代码下载请戳 —> Ios7LeftBarButtonItem.zip

转载：http://blog.yorkgu.me/2013/11/15/fix-position-of-leftbarbuttonitem-under-ios7/