自定义navigationbar左边的按钮

先放这里，以后复制就好~
viewdidload：

self.navigationItem.leftBarButtonItem = [self leftBarButtonItem];

其它函数：

- (UIBarButtonItem *)leftBarButtonItem{

  

    UIButton *left = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, 11, 20)];

    [left setBackgroundImage:[UIImage imageNamed:@"nav_back"] forState:UIControlStateNormal];

    [left addTarget:self action:@selector(popViewCon) forControlEvents:UIControlEventTouchUpInside];

    [left setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];

    [left setTitleColor:[UIColor blueColor] forState:UIControlStateHighlighted];

  

    UIBarButtonItem *item = [self barItemWithCustomView:left];

    return item;

}

- (UIBarButtonItem *)barItemWithCustomView:(id)custom{

    return [[UIBarButtonItem alloc]initWithCustomView:(UIView *)custom];

}

-(void)popViewCon

{

    [self.navigationController popViewControllerAnimated:YES];

}