如何在navigationBar加个Left,这些控件本身只能在固定位置上

先上代码

UIImage* backImage = [UIImage imageNamed:@"nav_order_more"];         
     CGRect backframe = CGRectMake(0,0,30,8);
     UIButton* backButton= [[UIButton alloc] initWithFrame:backframe]; 
     [backButton setBackgroundImage:backImage forState:UIControlStateNormal];
    backButton.titleLabel.font=[UIFont systemFontOfSize:13];
    [backButton addTarget:self action:@selector(doClickBackAction) forControlEvents:UIControlEventTouchUpInside];

    UIBarButtonItem* setRightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];     
    self.navigationItem.rightBarButtonItem = setRightBarButtonItem;

• UIImage -> UIButton -> UIBarButtonItem -> self.navigationItem
  • 通过initWithCustomView方法，实现UIButton -> UIBarButtonItem

怎么在navigationBar加Center,这些控件本身只能在固定位置上

JRSegmentControl *segment = [[JRSegmentControl alloc] 
   initWithFrame:CGRectMake(0, 0, self.itemWidth *  
   self.viewControllers.count, self.itemHeight) titles:self.titles]; 
   segment.backgroundColor = self.segmentBgColor; 
   segment.indicatorViewColor = self.indicatorViewColor; 
   segment.delegate = self; 
   self.navigationItem.titleView = segment;

• JRSegmentControl -> self.navigationItem.titleView
  • 通过赋值的方式 self.navigationItem.titleView = segment;

如何在navigationBar中的任意位置加控件

UISegmentedControl * contorl = [[UISegmentedControl alloc]  
   initWithItems:@[@"全部",@"待收货",@"待评价"]]; 
   contorl.frame = CGRectMake([UIScreen   
   mainScreen].bounds.size.width/2-150/2, 2, 150, 40);
   [contorl addTarget:self action:@selector(clickSegment:) 
   forControlEvents:UIControlEventValueChanged]; 
   //默认选择为第一个 
   contorl.selectedSegmentIndex = 0; 
   [self.navigationController.navigationBar addSubview:contorl];

• UISegmentedControl -> self.navigationController.navigationBar
• 通过addSubView的方式
  • [self.navigationController.navigationBar addSubview:cont

总结：

• 导航栏上只能加UIBarButton,item,不可加控件.