UINavigationController及顶部导航条

1. UINavigationController管理一个VC的栈，栈底的VC叫做这个UINavigationController的root view controller.
2. 有一个函数叫做popToRootViewController(animated:)，就是返回rootVC。

3. UINavigationController在顶部有一个navigationBar，继承自UIView。它的frame，bound及alpha值都不能改变。隐藏或者显示这个navigationBar要调用UINavigationController的setNavigationBarHidden(_:animated:)方法。其中动画的时间是一个常量UINavigationControllerHideShowBarDuration，不能改变。

   To show or hide the navigation bar, you should always do so through the navigation controller by changing its isNavigationBarHidden property or calling the setNavigationBarHidden(_:animated:) method.

               self.navigationController?.setNavigationBarHidden(false, animated: true)
               self.navigationController?.navigationBarHidden
   
   

4. navigationBar的各个属性
   

5. navigationBar的背景色

   self.navigationController?.navigationBar.barTintColor = UIColor.yellowColor()
   

   

6. navigationBar的配置
   navigationBar有左、中、右三个部分。显示的具体内容是根据当前VC的UINavigationItem属性及栈中前一个VC的UINavigationItem属性配置的。

7. UINavigationItem
   UINavigationItem作为VC的属性，在这个VC处于navigation stack时，用来设置定于导航条的样式等等。属性分别用来设置导航条左、中、右的样式等。

   • 左边

     • leftBarButtonItem 最左边的按钮
     • leftBarButtonItems 最左边的按钮们（可以有多个）
     • setLeftBarButtonItems(_:animated:)

     self.navigationItem.leftBarButtonItem = UIBarButtonItem.init(title: "left", style: .Plain, target: self, action: #selector(TGVCButtom.leftButtonClicked(_:)))
     self.navigationItem.leftBarButtonItem?.tintColor = UIColor.brownColor()
     let dict = [NSForegroundColorAttributeName : UIColor.blueColor(),
                 NSKernAttributeName: NSNumber.init(int: 10) 
     self.navigationItem.leftBarButtonItem?.setTitleTextAttributes(dict, forState: .Normal)
     
     let sencondleftBarButtonItem = UIBarButtonItem.init(title: "leftSecond", style: .Plain, target: self, action: #selector(TGVCButtom.secondLeftButtonClicked(_:)))  
     self.navigationItem.setLeftBarButtonItems([self.navigationItem.leftBarButtonItem!,sencondleftBarButtonItem], animated: true)
     

     

   • 中间

     • title

       self.navigationItem.title = "buttomVC"
       

     • titleView
       会覆盖title。如果需要设置button、富文本可以考虑这个

       Custom title views are centered on the navigation bar and may be resized to fit

       self.navigationItem.titleView = UIImageView.init(image: TGResizeImage(UIImage.init(named: "cat"), byRatio: 0.5) )
       

   • 右边。和左边类似。
     • rightBarButtonItem
       
     • rightBarButtonItems
     • setRightBarButtonItems(_:animated:)

   • 返回按钮
     
     有时候既要有一个返回的按钮，又要有一个左边的按钮。达到微信的网页常有的返回+关闭的效果。
     
     
     
     假设一个当前VC是A，push一个VC出去。

     self.navigationController?.pushViewController(self.topVC, animated:true)
     

     那么需要

     1. 设置自己的backBarButtonItem

        self.navigationItem.backBarButtonItem = UIBarButtonItem.init(title: "back", style: .Plain, target: nil, action: nil);
        

     2. 设置topVC的leftBarButtonItem

        self.navigationItem.leftBarButtonItem = UIBarButtonItem.init(title: "leftButton", style: .Done, target: self, action: nil)
        

     3. 设置topVC的两个变量

        self.navigationItem.hidesBackButton = false //返回按钮没有被隐藏
        self.navigationItem.leftItemsSupplementBackButton = true //返回按钮可以和左边的按钮一起出现
        

        

8. 奇怪的prompt

   A single line of text displayed at the top of the navigation bar

       self.navigationItem.prompt = "promt"//不知道干嘛的。。有啥用呢
   

   

9. 一个解释
   

10. 如何禁止左滑返回

    self.navigationController?.interactivePopGestureRecognizer?.enabled = false