解决 ios7.0 以后自定义导航栏左边按钮靠右的问题

  UIButton *backButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 30,30)];

    [backButton setTitleEdgeInsets:UIEdgeInsetsMake(-10.0, 0.0, 0.0, 0.0)];

    [backButton setImage:[UIImage imageNamed:@"back_icon"] forState:UIControlStateNormal];

    [backButton addTarget:self.navigationController action:@selector(popViewControllerAnimated:) forControlEvents:UIControlEventTouchUpInside];

    UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];

//    [self.navigationItem setLeftBarButtonItem:backItem];

  

    UIBarButtonItem *negativeSpacer = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace

                                                                                   target:nil action:nil];

    negativeSpacer.width = -10;//这个数值可以根据情况自由变化

    self.navigationItem.leftBarButtonItems = @[negativeSpacer,backItem];