出现部分导航栏标题不居中的原因的上一个视图的title文字过多的情况，引起本页面的返回按钮占居了很多位置将titleview挤到了右边，要解决这个问题，请在viewdidload中设置前一个视图的backBarButtonItem。
为了统一设置：利用了https://github.com/steipete/Aspects这个库注入方法。
方法如下：
[UIViewController aspect_hookSelector:@selector(viewDidLoad) withOptions:AspectPositionAfter usingBlock:^(id<AspectInfo> info) { UIViewController* infoVC = (UIViewController*)info.instance; NSArray *viewControllerArray = [infoVC.navigationController viewControllers]; if (viewControllerArray == nil) { return ; } long prevIoUsViewControllerIndex = [viewControllerArray indexOfObject:infoVC] - 1; UIViewController *prevIoUs; if (prevIoUsViewControllerIndex >= 0 && prevIoUsViewControllerIndex < viewControllerArray.count) { prevIoUs = [viewControllerArray objectAtIndex:prevIoUsViewControllerIndex]; if (prevIoUs.title.length < 4){ return ; } prevIoUs.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"xx" style:UIBarButtonItemStylePlain target:self action:nil]; } } error:NULL];
