發(fā)現(xiàn)問題

全局管理和局部管理狀態(tài)欄

iOS 7 以前，我們只有基于 UIApplication 單例類的全局狀態(tài)欄管理：

extension UIApplication {
    // Setting the statusBarStyle does nothing if your application is using the default UIViewController-based status bar system.
    @available(iOS, introduced: 2.0, deprecated: 9.0, message: "Use -[UIViewController preferredStatusBarStyle]")
    open func setStatusBarStyle(_ statusBarStyle: UIStatusBarStyle, animated: Bool)
    
    // Setting statusBarHidden does nothing if your application is using the default UIViewController-based status bar system.
    @available(iOS, introduced: 3.2, deprecated: 9.0, message: "Use -[UIViewController prefersStatusBarHidden]")
    open func setStatusBarHidden(_ hidden: Bool, with animation: UIStatusBarAnimation)
}

我們使用起來大概這樣：

// 設(shè)置狀態(tài)欄樣式
UIApplication.shared.statusBarStyle = .default
// 設(shè)置狀態(tài)欄是否隱藏
UIApplication.shared.isStatusBarHidden = false
// 設(shè)置狀態(tài)欄是否隱藏店茶，變化過程是否需要?jiǎng)赢?UIApplication.shared.setStatusBarHidden(false, with: .fade)

但在 iOS 7 以后蛹找，蘋果推出了另外一套狀態(tài)欄管理機(jī)制姨伤，即基于控制器的局部狀態(tài)欄管理，從官方注釋可以看出這種機(jī)制是蘋果推薦使用的：

extension UIViewController {
    @available(iOS 7.0, *)
    open var preferredStatusBarStyle: UIStatusBarStyle { get } // Defaults to UIStatusBarStyleDefault

    @available(iOS 7.0, *)
    open var prefersStatusBarHidden: Bool { get } // Defaults to NO

    // Override to return the type of animation that should be used for status bar changes for this view controller. This currently only affects changes to prefersStatusBarHidden.
    @available(iOS 7.0, *)
    open var preferredStatusBarUpdateAnimation: UIStatusBarAnimation { get } // Defaults to UIStatusBarAnimationFade

    // 手動(dòng)觸發(fā)狀態(tài)欄狀態(tài)更新
    @available(iOS 7.0, *)
    open func setNeedsStatusBarAppearanceUpdate()
}

我們使用起來大概這樣：

class ViewController: UIViewController {
    // 狀態(tài)欄是否隱藏
    override var prefersStatusBarHidden: Bool {
        return false
    }
    // 狀態(tài)欄樣式
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return .default
    }
    // 狀態(tài)欄隱藏動(dòng)畫
    override var preferredStatusBarUpdateAnimation: UIStatusBarAnimation {
        return .fade
    }
}

默認(rèn)情況下熄赡，狀態(tài)欄都是基于控制器的狀態(tài)管理姜挺，這 2 種狀態(tài)欄管理機(jī)制可以通過在 info.plist 修改配置進(jìn)行選擇

基于控制器的全局管理單例類

2 種管理狀態(tài)欄的形式各有優(yōu)缺點(diǎn)：

全局管理

• 優(yōu)點(diǎn)：管理方便，代碼簡(jiǎn)潔
• 缺點(diǎn)：狀態(tài)是全局共享的彼硫，相互影響

局部管理

• 優(yōu)點(diǎn)：狀態(tài)是分離到各個(gè)控制器炊豪，互不影響
• 缺點(diǎn)：管理不方便凌箕，管理代碼分散到各個(gè)控制器

我想結(jié)合了這 2 種管理機(jī)制的優(yōu)點(diǎn)，開發(fā)一個(gè)基于控制器的全局管理單例類 StatusBarManager词渤，即能像 UIApplication 那樣簡(jiǎn)潔的管理狀態(tài)欄牵舱，又能像 UIViewController 那樣分離的管理狀態(tài)欄。

分析問題

基于控制器的全局管理實(shí)現(xiàn)

首先我們就需要先把基于控制器的管理狀態(tài)欄轉(zhuǎn)變成單例類管理狀態(tài)欄缺虐，這很簡(jiǎn)單芜壁，類似下面這樣實(shí)現(xiàn)，具體內(nèi)部實(shí)現(xiàn)下面會(huì)給出源碼：

/// 自定義基類控制器高氮，重載 prefersStatusBarHidden 等方法
class BasicViewController: UIViewController {
    
    override var prefersStatusBarHidden: Bool {
        return StatusBarManager.shared.isHidden
    }
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return StatusBarManager.shared.style
    }
    override var preferredStatusBarUpdateAnimation: UIStatusBarAnimation {
        return StatusBarManager.shared.animation
    }
}

分離的狀態(tài)欄狀態(tài)實(shí)現(xiàn)

實(shí)現(xiàn)分離的狀態(tài)管理才是我們的重點(diǎn)慧妄，不然我們直接使用全局管理就行了，沒必要這么麻煩剪芍，首先我們要理解什么是分離的狀態(tài)管理塞淹，先看下圖：

當(dāng)我們顯示前面視圖時(shí)，后面視圖的狀態(tài)欄變化是不會(huì)影響到前面視圖的狀態(tài)欄狀態(tài)罪裹，這就是狀態(tài)欄狀態(tài)的分離饱普。

要實(shí)現(xiàn)這個(gè)功能，我聯(lián)系到控制器導(dǎo)航使用的是 push 和 pop 操作状共，present 和 dismiss 操作也可以看成一個(gè) push 和 pop 操作套耕，我就想那我的狀態(tài)欄狀態(tài)是否也能通過 push 和 pop 進(jìn)行管理呢？

看起來是可以峡继，但我們要想到另外一個(gè)問題冯袍，那就是分頁控制器用 push 和 pop 管理狀態(tài)欄狀態(tài)是不行的，因?yàn)槭峭瑢蛹?jí)控制器鬓椭，那就需要有多分支的存儲(chǔ)結(jié)構(gòu)颠猴，不能用線性表結(jié)構(gòu)，我想到了數(shù)據(jù)結(jié)構(gòu)里的樹結(jié)構(gòu)小染！再仔細(xì)一想翘瓮，UIView 視圖層次不就是一個(gè)樹結(jié)構(gòu)嗎？好裤翩，就決定是你了Ｗ手选！踊赠！

解決問題

樹結(jié)構(gòu)示意圖：

import UIKit

/// 狀態(tài)欄單一狀態(tài)節(jié)點(diǎn)
class StatusBarState: NSObject {
    static let defaultKey: String = "StatusBarState.default.root.key"
    
    var isHidden: Bool = false
    var style: UIStatusBarStyle = .lightContent
    var animation: UIStatusBarAnimation = .fade
    var key: String = defaultKey
    // 子節(jié)點(diǎn)數(shù)組
    var subStates: [StatusBarState] = []
    // 父節(jié)點(diǎn)呵扛，為 nil 說明是根節(jié)點(diǎn)
    weak var superState: StatusBarState?
    // 下一個(gè)路徑節(jié)點(diǎn)，為 nil 說明是葉子節(jié)點(diǎn)
    weak var nextState: StatusBarState?
    
    override var description: String {
        return "{ key=\(self.key) selected=\(String(describing: self.nextState?.key)) }"
    }
}

/// 全局狀態(tài)欄狀態(tài)管理單例類
class StatusBarManager {
    static let shared = StatusBarManager()
    // MARK: - 屬性
    /// 狀態(tài)鍵集合筐带，用來判斷樹中是否有某個(gè)狀態(tài)
    fileprivate var stateKeys: Set<String> = Set<String>()
    /// 根節(jié)點(diǎn)狀態(tài)今穿，從這個(gè)根節(jié)點(diǎn)可以遍歷到整個(gè)狀態(tài)樹
    fileprivate var rootState: StatusBarState!
    /// 更新狀態(tài)欄動(dòng)畫時(shí)間
    fileprivate var duration: TimeInterval = 0.1
    /// 當(dāng)前狀態(tài)
    fileprivate var currentState: StatusBarState!
    
    /// 以下3個(gè)計(jì)算屬性都是取當(dāng)前狀態(tài)顯示以及更新當(dāng)前狀態(tài)
    var isHidden: Bool {
        get {
            return currentState.isHidden
        }
        set {
            setState(for: currentState.key, isHidden: newValue)
        }
    }
    var style: UIStatusBarStyle {
        get {
            return currentState.style
        }
        set {
            setState(for: currentState.key, style: newValue)
        }
    }
    var animation: UIStatusBarAnimation {
        get {
            return currentState.animation
        }
        set {
            setState(for: currentState.key, animation: newValue)
        }
    }
    
    // MARK: - 方法
    /// 初始化根節(jié)點(diǎn)
    fileprivate init() {
        rootState = StatusBarState()
        currentState = rootState
        stateKeys.insert(rootState.key)
    }
    
    /// 為某個(gè)狀態(tài)(root)添加子狀態(tài)(key)，當(dāng) root = nil 時(shí)伦籍，表示添加到根狀態(tài)上
    @discardableResult
    func addSubState(with key: String, root: String? = nil) -> StatusBarState? {
        guard !stateKeys.contains(key) else { return nil }
        stateKeys.insert(key)
        
        let newState = StatusBarState()
        newState.key = key
        
        // 找到鍵為 root 的父狀態(tài)
        var superState: StatusBarState! = rootState
        if let root = root {
            superState = findState(root)
        }
        newState.isHidden = superState.isHidden
        newState.style = superState.style
        newState.animation = superState.animation
        newState.superState = superState
        
        // 添加進(jìn)父狀態(tài)的子狀態(tài)集合中蓝晒，默認(rèn)選中第一個(gè)
        superState.subStates.append(newState)
        if superState.nextState == nil {
            superState.nextState = newState
        }
        
        // 判斷是否在當(dāng)前狀態(tài)上添加子狀態(tài)腮出，是的話，自動(dòng)切換當(dāng)前狀態(tài)
        if currentState.key == superState.key {
            currentState = newState
            updateStatusBar()
        }
        
        printAllStates()
        return newState
    }
    
    /// 刪除某個(gè)狀態(tài)及其子狀態(tài)樹
    func removeState(with key: String) {
        guard stateKeys.contains(key) else { return }
        let state = findState(key)
        let isContainCurrentState = findStateInTree(state, key: currentState.key) != nil
        if state.subStates.count > 0 {
            removeSubStatesInTree(state)
        }
        // 是否有父狀態(tài)芝薇，如果沒有胚嘲，說明要?jiǎng)h除的是根狀態(tài)，根節(jié)點(diǎn)是不能刪除的洛二，否則刪除該節(jié)點(diǎn)并切換當(dāng)前狀態(tài)
        if let superState = state.superState {
            stateKeys.remove(state.key)
            if let index = superState.subStates.index(of: state) {
                superState.subStates.remove(at: index)
            }
            superState.nextState = superState.subStates.first
            if isContainCurrentState {
                if let selectedState = superState.nextState {
                    currentState = selectedState
                } else {
                    currentState = superState
                }
                updateStatusBar()
            }
            
        }
        printAllStates()
    }
    
    /// 更改某個(gè)狀態(tài)(root)下要顯示直接的子狀態(tài)節(jié)點(diǎn)(key)
    func showState(for key: String, root: String? = nil) {
        guard stateKeys.contains(key) else { return }
        
        // 改變父狀態(tài) nextState 屬性
        let rootState = findState(root)
        for subState in rootState.subStates {
            if subState.key == key {
                rootState.nextState = subState
                break
            }
        }
        // 找到切換后的當(dāng)前狀態(tài)
        let newCurrentState = findCurrentStateInTree(rootState)
        if newCurrentState != currentState {
            currentState = newCurrentState
            updateStatusBar()
        }
        printAllStates()
    }
    
    /// 刪除某個(gè)狀態(tài)下的子狀態(tài)樹
    func clearSubStates(with key: String, isUpdate: Bool = true) {
        guard stateKeys.contains(key) else { return }
        let state = findState(key)
        var needUpdate: Bool = false
        if findStateInTree(state, key: currentState.key) != nil {
            currentState = state
            needUpdate = true
        }
        if state.subStates.count > 0 {
            removeSubStatesInTree(state)
        }
        if needUpdate && isUpdate {
            updateStatusBar()
        }
        printAllStates()
    }
    
    /// 負(fù)責(zé)打印狀態(tài)樹結(jié)構(gòu)
    func printAllStates(_ method: String = #function) {
        debugPrint("\(method): currentState = \(currentState.key)")
        printAllStatesInTree(rootState, deep: 0, method: method)
    }

    /// 更新棧中 key 對(duì)應(yīng)的狀態(tài)馋劈，key == nil 表示棧頂狀態(tài)
    func setState(for key: String? = nil, isHidden: Bool? = nil, style: UIStatusBarStyle? = nil, animation: UIStatusBarAnimation? = nil) {
        var needUpdate: Bool = false
        let state = findState(key)
        if let isHidden = isHidden, state.isHidden != isHidden {
            needUpdate = true
            state.isHidden = isHidden
        }
        if let style = style, state.style != style {
            needUpdate = true
            state.style = style
        }
        if let animation = animation, state.animation != animation {
            needUpdate = true
            state.animation = animation
        }
        // key != nil 表示更新對(duì)應(yīng) key 的狀態(tài)，需要判斷該狀態(tài)是否是當(dāng)前狀態(tài)
        if let key = key {
            guard let currentState = currentState, currentState.key == key else { return }
        }
        // 狀態(tài)有變化才需要更新視圖
        if needUpdate {
            updateStatusBar()
        }
    }
    
    /// 開始更新狀態(tài)欄的狀態(tài)
    fileprivate func updateStatusBar() {
        DispatchQueue.main.async { // 在主線程異步執(zhí)行 避免同時(shí)索取同一屬性
            // 如果狀態(tài)欄需要?jiǎng)赢嫞╢ade or slide）晾嘶，需要添加動(dòng)畫時(shí)間妓雾，才會(huì)有動(dòng)畫效果
            UIView.animate(withDuration: self.duration, animations: {
                UIApplication.shared.keyWindow?.rootViewController?.setNeedsStatusBarAppearanceUpdate()
            })
        }
    }
    
    /// 從狀態(tài)樹中找到對(duì)應(yīng)的節(jié)點(diǎn)狀態(tài)，沒找到就返回根節(jié)點(diǎn)
    fileprivate func findState(_ key: String? = nil) -> StatusBarState {
        if let key = key { // 查找
            if let findState = findStateInTree(rootState, key: key) {
                return findState
            }
        }
        return rootState
    }
    
    /// 從狀態(tài)樹中找到對(duì)應(yīng)的節(jié)點(diǎn)狀態(tài)的遞歸方法
    fileprivate func findStateInTree(_ state: StatusBarState, key: String) -> StatusBarState? {
        if state.key == key {
            return state
        }
        for subState in state.subStates {
            if let findState = findStateInTree(subState, key: key) {
                return findState
            }
        }
        return nil
    }
    
    /// 刪除某個(gè)狀態(tài)下的所有子狀態(tài)的遞歸方法
    fileprivate func removeSubStatesInTree(_ state: StatusBarState) {
        state.subStates.forEach { (subState) in
            stateKeys.remove(subState.key)
            removeSubStatesInTree(subState)
        }
        state.subStates.removeAll()
    }
    
    /// 找到某個(gè)狀態(tài)下的最底層狀態(tài)
    fileprivate func findCurrentStateInTree(_ state: StatusBarState) -> StatusBarState? {
        if let nextState = state.nextState {
            return findCurrentStateInTree(nextState)
        }
        return state
    }
    
    /// 打印狀態(tài)樹結(jié)構(gòu)的遞歸方法
    fileprivate func printAllStatesInTree(_ state: StatusBarState, deep: Int = 0, method: String) {
        debugPrint("\(method): \(deep) - state=\(state)")
        for subState in state.subStates {
            printAllStatesInTree(subState, deep: deep + 1, method: method)
        }
    }
}

創(chuàng)建 UIViewController+StatusBar 分類和基類控制器來輔助設(shè)置垒迂，簡(jiǎn)單管理狀態(tài)欄：

/// UIViewController+StatusBar.swift
import UIKit

extension UIViewController {
    
    /// 控制器的狀態(tài)欄唯一鍵
    var statusBarKey: String {
        return "\(self)"
    }
    
    /// 設(shè)置該控制器的狀態(tài)欄狀態(tài)
    func setStatusBar(isHidden: Bool? = nil, style: UIStatusBarStyle? = nil, animation: UIStatusBarAnimation? = nil) {
        StatusBarManager.shared.setState(for: statusBarKey, isHidden: isHidden, style: style, animation: animation)
    }

    /// 添加一個(gè)子狀態(tài)
    func addSubStatusBar(for viewController: UIViewController) {
        let superKey = self.statusBarKey
        let subKey = viewController.statusBarKey
        StatusBarManager.shared.addSubState(with: subKey, root: superKey)
    }
    
    /// 批量添加子狀態(tài)君珠，樹橫向生長(zhǎng)
    func addSubStatusBars(for viewControllers: [UIViewController]) {
        viewControllers.forEach { (viewController) in
            self.addSubStatusBar(for: viewController)
        }
    }
    
    /// 從整個(gè)狀態(tài)樹上刪除當(dāng)前狀態(tài)
    func removeFromSuperStatusBar() {
        let key = self.statusBarKey
        StatusBarManager.shared.removeState(with: key)
    }
    
    /// 設(shè)置當(dāng)前狀態(tài)下的所有子狀態(tài)
    func setSubStatusBars(for viewControllers: [UIViewController]?) {
        clearSubStatusBars()
        if let viewControllers = viewControllers {
            addSubStatusBars(for: viewControllers)
        }
    }
    
    /// 通過類似壓棧的形式，壓入一組狀態(tài)娇斑，樹縱向生長(zhǎng)
    func pushStatusBars(for viewControllers: [UIViewController]) {
        var lastViewController: UIViewController? = self
        viewControllers.forEach { (viewController) in
            if let superController = lastViewController {
                superController.addSubStatusBar(for: viewController)
                lastViewController = viewController
            }
        }
    }
    
    /// 切換多個(gè)子狀態(tài)的某個(gè)子狀態(tài)
    func showStatusBar(for viewController: UIViewController?) {
        guard let viewController = viewController else { return }
        let superKey = self.statusBarKey
        let subKey = viewController.statusBarKey
        StatusBarManager.shared.showState(for: subKey, root: superKey)
    }
    
    /// 清除所有子狀態(tài)
    func clearSubStatusBars(isUpdate: Bool = true) {
        StatusBarManager.shared.clearSubStates(with: self.statusBarKey, isUpdate: isUpdate)
    }
}

/// 保證所有控制器都重載了 prefersStatusBarHidden 的方法
class BasicViewController: UIViewController {
    
    override var prefersStatusBarHidden: Bool {
        return StatusBarManager.shared.isHidden
    }
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return StatusBarManager.shared.style
    }
    override var preferredStatusBarUpdateAnimation: UIStatusBarAnimation {
        return StatusBarManager.shared.animation
    }

    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    deinit {
         self.removeFromSuperStatusBar()
    }
    
    override func present(_ viewControllerToPresent: UIViewController, animated flag: Bool, completion: (() -> Void)? = nil) {
        self.addSubStatusBar(for: viewControllerToPresent)
        super.present(viewControllerToPresent, animated: flag, completion: completion)
    }
}

/// 保證所有控制器都重載了 prefersStatusBarHidden 的方法
class BasicNavigationController: UINavigationController {
    
    override var prefersStatusBarHidden: Bool {
        return StatusBarManager.shared.isHidden
    }
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return StatusBarManager.shared.style
    }
    override var preferredStatusBarUpdateAnimation: UIStatusBarAnimation {
        return StatusBarManager.shared.animation
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        pushStatusBars(for: viewControllers)
    }
    
    override func setViewControllers(_ viewControllers: [UIViewController], animated: Bool) {
        clearSubStatusBars(isUpdate: false)
        pushStatusBars(for: viewControllers)
        super.setViewControllers(viewControllers, animated: animated)
    }
    
    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        topViewController?.addSubStatusBar(for: viewController)
        super.pushViewController(viewController, animated: animated)
    }
}

/// 保證所有控制器都重載了 prefersStatusBarHidden 的方法
class BasicTabBarController: UITabBarController, UITabBarControllerDelegate {
    
    override var prefersStatusBarHidden: Bool {
        return StatusBarManager.shared.isHidden
    }
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return StatusBarManager.shared.style
    }
    override var preferredStatusBarUpdateAnimation: UIStatusBarAnimation {
        return StatusBarManager.shared.animation
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        self.setSubStatusBars(for: viewControllers)
        self.delegate = self
    }
    
    override func setViewControllers(_ viewControllers: [UIViewController]?, animated: Bool) {
        self.setSubStatusBars(for: viewControllers)
        super.setViewControllers(viewControllers, animated: animated)
    }
    
    func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
        showStatusBar(for: viewController)
    }
}

基于控制器的全局狀態(tài)欄使用：

class ViewController: BasicViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        setStatusBar(isHidden: false, style: .default)
    }
}

Demo 源碼在這里：StatusBarManagerDemo

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