#define   IOS7_NAVI_SPACE   -10

}

    [self.navigationItem setLeftBarButtonItems:[self getBackBarButtonitem]];

}

//返回按钮

-(NSArray *)getBackBarButtonitem{

    //自定义button

    UIButton *button=[[UIButton alloc] initWithFrame:CGRectMake(, , , )];

    //设置背景图片

    [button setBackgroundImage:[UIImage imageNamed:@"nav_left_btn_unselected.png"] forState:UIControlStateNormal];

    //设置文字

    [button setTitle:@"返回" forState:UIControlStateNormal];

    button.titleLabel.font=[UIFont systemFontOfSize:];

    //设置文字颜色

    [button setTintColor:[UIColor whiteColor]];

    //为TouchUpInside添加行为

    [button addTarget:self action:@selector(backAction) forControlEvents:UIControlEventTouchUpInside];

    //初始化一个BarbuttonItem

    UIBarButtonItem *Item=[[UIBarButtonItem alloc] initWithCustomView:button];

    

    //在初始化一个系统的带有固定距离的占位的BarButtonItem 占位用

    UIBarButtonItem *fixedSpace=[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:self action:nil];

    fixedSpace.width=IOS7_NAVI_SPACE;//设置宽度
// 把带固定距离的Item放在前面，调整距离

    return [[NSArray alloc] initWithObjects:fixedSpace,Item, nil];

}