navigationBar相关

---

怎么在navigationBar加个Left(左右) .这些控件本身只能在固定位置上

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* setLeftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
    self.navigationItem.leftBarButtonItem = setLeftBarButtonItem;

//设置Button的背景图片，把Button放到BarButtonItem上，通过initWithCustomView的方式加到self.navigationItem.leftBarButtonItem = setLeftBarButtonItem上。

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

怎么在navigationBar加个Center(中间),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;
  //实例化个控件，设置它的fame(坐标和大小)，通过赋值的方式self.navigationItem.titleView,由于titleView继承的UIView，所以它可以是任何控件。

如何在navigationBar在任意位置加空间

 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:contorl];
  //实例化个控件，设置它的fame(坐标和大小)，通过addSubView的方式加到self.navigationController.navigationBar上。

---

总结：

导航栏上只能加UIBarButton,item(项目),不可加控件。