想實現(xiàn)這樣跳轉(zhuǎn)方法，原本就知道兩個UINavigationController不能相互跳轉(zhuǎn)，并且也懶得做自定義modal跳轉(zhuǎn)動畫，于是研究了三個小時總算有了兩種實現(xiàn)方法

簡書APP PUSH跳轉(zhuǎn)

簡書APP PUSH跳轉(zhuǎn)

第一種：在viewWillAppear中設(shè)置nav bar的隱藏與顯示

1. 在AppDelegate中設(shè)置rootVC為含有nav的ViewController

self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
self.window?.makeKeyAndVisible()
let vc = ViewController()
self.window?.rootViewController = UINavigationController(rootViewController: vc)

2. ViewController：
   在viewWillAppear中設(shè)置nav bar的隱藏

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
    // 動畫必須設(shè)置為true，否則會導(dǎo)致轉(zhuǎn)場動畫是nav bar不顯示
    self.navigationController?.setNavigationBarHidden(true, animated: true) 
}

隨意添加一個按鈕實現(xiàn)跳轉(zhuǎn)

屏幕快照 2016-05-19 下午7.01.08.png

3. 在SecondViewController中設(shè)置顯示nav bar
   同樣在viewWillAppear設(shè)置nav bar為顯示

override func viewDidLoad() {
    super.viewDidLoad()
    self.view.backgroundColor = UIColor.whiteColor()
    
    self.navigationItem.title = "首頁"
   
    // 最好不要設(shè)置leftBarButton，會導(dǎo)致pop手勢失效
    // self.navigationItem.leftBarButtonItem = UIBarButtonItem(title: "下一頁", style: .Done, target: self, action: #selector(self.returnAction))
}
override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
    self.navigationController?.setNavigationBarHidden(false, animated: true)
}

這樣就實現(xiàn)了從無item到有item的跳轉(zhuǎn)：

1.gif

4. 在ViewController中添加一個自定義的UINavigationBar

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.whiteColor()
        // 一定要設(shè)置nav的view的顏色，否則在跳轉(zhuǎn)時自定義的bar右上角會有黑色。但是如果將自定義的bar設(shè)置為其他View（比如UIView）就不會有這種現(xiàn)象
        self.navigationController?.view.backgroundColor = UIColor.whiteColor()
        
        let customBar = UINavigationBar(frame: CGRectMake(0, 0, self.view.frame.width, 64))
        self.view.addSubview(customBar)
        
        let customItem = UINavigationItem(title: "首頁")
        customItem.leftBarButtonItem = UIBarButtonItem(title: "進(jìn)入", style: .Done, target: self, action: #selector(self.next))
        customBar.items = [customItem]
}

效果：

2.gif

第二種：封裝基類，直接隱藏掉nav bar，添加一個自定義的bar，繼承基類即會實現(xiàn)該效果，方便使用

BaseViewController：

class BaseViewController: UIViewController {
    
    // 使用自定義的navigationItem
    // 不能使用原本的navigationItem，當(dāng)pop回來后里面的item會消失，可能和生命周期有關(guān)，不知道它都干了些什么
    var customNavigationItem = UINavigationItem(title: "")
    
    // 怎么私有化navigationItem?。?！這樣會失敗
//    override private var navigationItem: UINavigationItem
//    override private var navigationItem: UINavigationItem
//    override private var navigationItem: UINavigationItem
//    override private var navigationItem: UINavigationItem {
//        get{
//            return self.navigationItem
//        }
//    }

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.whiteColor()
        // 隱藏原本的nav
        self.navigationController?.view.backgroundColor = UIColor.whiteColor() // 需要設(shè)置點顏色，否則push時右上角會顯示一段黑色
        // 必須設(shè)置這兩個屬性，否則會導(dǎo)致pop手勢失效
        self.navigationController?.navigationBar.shadowImage = UIImage()
        self.navigationController?.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: .Default)
        self.navigationController?.navigationBar.hidden = true

        // 不能使用這個方法，會導(dǎo)致pop手勢失效，也不能把bar removeFromSuperView
//        self.navigationController?.setNavigationBarHidden(true, animated: true)
        
        // 自定義的nav bar，直接加到view上
        let customBar = UINavigationBar(frame: CGRectMake(0, 0, self.view.frame.width, 64))
        self.view.addSubview(customBar)
        
        // 設(shè)置item
        customBar.items = [customNavigationItem]
    }
}

使用：
ViewController：

class ViewController: BaseViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.customNavigationItem.title = "首頁"
        self.customNavigationItem.leftBarButtonItem = UIBarButtonItem(title: "下一頁", style: .Done, target: self, action: #selector(self.next))
    }
    
    func next() {
        let sec = SecondViewController()
        self.navigationController?.pushViewController(sec, animated: true)
    }
}

SecondViewCotroller：

class SecondViewController: BaseViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.whiteColor()
        
        self.customNavigationItem.title = "第二頁"
        self.customNavigationItem.leftBarButtonItem = UIBarButtonItem(title: "返回", style: .Done, target: self, action: #selector(self.returnAction))
    }
    
    func returnAction() {
        self.navigationController?.popViewControllerAnimated(true)
    }
}

效果：

3.gif