一。自定义navigationbar

 

- (void)initNavigationBar{    [self.navigationController setNavigationBarHidden:YES];    UINavigationBar *bar = [[UINavigationBar alloc] initWithFrame:CGRectMake(0, 0, 320, 32)];    [bar setBackgroundImage:[UIImage imageNamed:@"zhuche_bar2.png"] forBarMetrics:UIBarMetricsDefault];     UINavigationItem *item = [[UINavigationItem alloc] initWithTitle:nil];    UIButton *left = [UIButton buttonWithType:UIButtonTypeCustom];    [left setFrame:CGRectMake(0, 2, 28, 28)];    [left setImage:[UIImage imageNamed:@"zhuche_back.png"] forState:UIControlStateNormal];    [left addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];    UIBarButtonItem *leftButton = [[UIBarButtonItem alloc] initWithCustomView:left];    [item setLeftBarButtonItem:leftButton];    [bar pushNavigationItem:item animated:NO];    [self.view addSubview:bar];}- (void)back{    [self.navigationController popViewControllerAnimated:YES];}

虽然可以解决自定义navigationbar的问题，左右按钮都可以替换，但是如果放在UITableViewController中，自定义的navigationbar会随着scrollview的滑动而滑动，不会像系统自带的navigationbar一样始终保持在屏幕最上方。那么我们可以有第二种解决方式，修改原来的navigationbar，其实就是改一下leftBarButtonItem或者rightBarButtonItem在navigationbar上面的位置：修改UIBarButtonItem 的边距。

二。修改UIBarButtonItem 的边距

@interface UINavigationItem (margin)@end@implementation UINavigationItem (margin)#if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_6_1- (void)setLeftBarButtonItem:(UIBarButtonItem *)_leftBarButtonItem{    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)    {        UIBarButtonItem *negativeSeperator = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];        negativeSeperator.width = -16;//此处修改到边界的距离，请自行测试                if (_leftBarButtonItem)        {            [self setLeftBarButtonItems:@[negativeSeperator, _leftBarButtonItem]];        }        else        {            [self setLeftBarButtonItems:@[negativeSeperator]];        }                   }    else    {        [self setLeftBarButtonItem:_leftBarButtonItem animated:NO];    }}- (void)setRightBarButtonItem:(UIBarButtonItem *)_rightBarButtonItem{    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)    {        UIBarButtonItem *negativeSeperator = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];        negativeSeperator.width = -12;//此处修改到边界的距离，请自行测试                if (_rightBarButtonItem)        {            [self setRightBarButtonItems:@[negativeSeperator, _rightBarButtonItem]];        }        else        {            [self setRightBarButtonItems:@[negativeSeperator]];        }            }    else    {        [self setRightBarButtonItem:_rightBarButtonItem animated:NO];    }}#endif@end

以上代码可以放置在主视图控制器的.m文件里面，@implementation ViewController的上面。

参考资料：http://blog.csdn.net/reylen/article/details/16338781；

http://blog.163.com/lhl_soft/blog/static/201750004201292043750125/；