网络浏览器的工作历史如何

如何解决网络浏览器的工作历史如何

我正在尝试为 iOS 上的 WKWebView 实现我自己的网络浏览器历史记录，但我无法完全实现此功能，并且每次遇到麻烦。 我可以创建用户所在的历史记录，然后在历史记录中前后移动。 但我有下一个麻烦，我认为这只是我路上的众多问题之一。 例如，当我有一个包含 10 个元素的历史记录，然后我移回第 5 个元素，然后不要转发但尝试打开新链接时，我无法删除元素 6-10 并放置新链接。

我认为我的问题是我无法完全理解历史在所有浏览器内部的工作原理，这不是一项艰巨的任务，但我对这个算法感到困惑。 我保存历史的主要数据结构 帮助我了解如何在浏览器中使用此算法，或者是否存在关于它的好理论？

解决方法

我已经解决了这个问题并且很好地实现了完整的算法，完整的项目可以在这里找到：https://github.com/IhorYachmenov/Custom-browser-history-for-WKWebView。

算法：

struct PlayerHistory {
    
    static var shared = PlayerHistory()
    
    var historyExist: Bool = false
    var historyCurrentPosition: Int = 0
    var historyLastPositionBeforeUpdatingHistory: Int!
    var userHistoryKey: String!
    
    var backPressed: Bool!
    var forwardPressed: Bool!
    
    var urlOfPlayer: String!
    
    // Function only for first loading inside <viewDidLoad or another method from app LifeCycle>.
    mutating func getUrlForFirstLoading(initURL: String,key: String) -> String {
        
        urlOfPlayer = initURL
        
        guard HistoryStorage.shared.getHistoryFromUserDefaults() != nil else {
            updateFirstElement(key: key,url: initURL)
            return initURL
        }
        
        guard HistoryStorage.shared.getHistoryFromUserDefaults()![key] != nil else {
            return initURL
        }
        
        let position = HistoryStorage.shared.getHistoryFromUserDefaults()![key]!.count - 1
        
        historyExist = true
        historyCurrentPosition = position
        userHistoryKey = key
        let initUrlFromHistoryStorage = HistoryStorage.shared.getHistoryFromUserDefaults()![key]!.last!.url
        
        return initUrlFromHistoryStorage
    }
    
    // Create new or update exist history,use this method indsede <decidePolicyForNavigation>.
    mutating func updatePlayerHistory(backlisk: [String],key: String) {
        
        var history = [WebViewHistory]()
        
        for i in backlisk {
            history.append(WebViewHistory(i))
        }
        
        if (historyExist == true) {
            // If old history exist need compound both and then to save.
            
            let oldHistory = HistoryStorage.shared.getHistoryFromUserDefaults()![key]

            let oldAndNewHostoryTogether = oldHistory! + history
            
            var keyValuePair = Dictionary<String,[WebViewHistory]>()
            keyValuePair.updateValue(oldAndNewHostoryTogether,forKey: key)
            
            HistoryStorage.shared.removeHistory()
            HistoryStorage.shared.saveHistory(keyValuePair)
            
            setCurrentPosition(url: backlisk.last!,key: key)
        } else {
            var keyValuePair = Dictionary<String,[WebViewHistory]>()
            keyValuePair.updateValue(history,forKey: key)
            
            historyExist = true
            
            HistoryStorage.shared.removeHistory()
            HistoryStorage.shared.saveHistory(keyValuePair)
            setCurrentPosition(url: backlisk.last!,key: key)
        }
    }
        
    
    // Before using this method check if result don't equals nil. Use this method for navigation beetween history
    func moveThroughHistory(key: String,direction: Bool) -> String? {
        
        guard  historyExist != false else {
            return nil
        }
        
        let history = HistoryStorage.shared.getHistoryFromUserDefaults()![key]!
        
        if (direction == true) {
            let index = historyCurrentPosition + 1
            guard index != history.count else { return nil }
            return history[index].url
        } else {
            let index = historyCurrentPosition - 1
            guard index > 0 else { return history[0].url }
            return history[index].url
        }
        
        
    }
    
    // Method <setCurrentPosition> each time set position at history
    mutating func setCurrentPosition(url: String,key: String) {
        
        guard HistoryStorage.shared.getHistoryFromUserDefaults() != nil else { return }
        guard HistoryStorage.shared.getHistoryFromUserDefaults()![key] != nil else { return }
        
        let history = HistoryStorage.shared.getHistoryFromUserDefaults()![key]
        let index = history?.firstIndex(of: WebViewHistory(url))
        
        guard index != nil else {
            historyCurrentPosition = 0
            return
        }
        historyCurrentPosition = index!
    }
    
    // <removeUnusedPeaceOfHistory> need use when user want open new page staying inside the middle of history
    mutating func removeUnusedPeaceOfHistory(key: String) {
        
        guard HistoryStorage.shared.getHistoryFromUserDefaults() != nil else {
            return
        }
        
        guard HistoryStorage.shared.getHistoryFromUserDefaults()![key] != nil else {
            return
        }
        
        var history = HistoryStorage.shared.getHistoryFromUserDefaults()![key]!
        let startIndex = historyCurrentPosition + 1
        let endIndex = history.endIndex - 1
        let countOfAllElements = history.count
        
        guard startIndex != countOfAllElements else { return }
        let range = startIndex...endIndex
        history.removeSubrange(range)
        
        var keyValuePair = Dictionary<String,[WebViewHistory]>()
        keyValuePair.updateValue(history,forKey: key)
        
        HistoryStorage.shared.removeHistory()
        HistoryStorage.shared.saveHistory(keyValuePair)
    }
        
    // Use <updateFirstElement> inside <getUrlForFirstLoading> if history doesn't exist
    private mutating func updateFirstElement(key: String,url: String) {
        var history = [WebViewHistory]()
        history.insert(WebViewHistory(url),at: 0)
        
        var keyValuePair = Dictionary<String,forKey: key)
        
        HistoryStorage.shared.saveHistory(keyValuePair)
        historyExist = true
        historyCurrentPosition = 0
        
    }
    
    // Use <webViewWillBeClosedSaveHistory> when WKWebView should be closed,if the user moves through history new position will be saved.
    mutating func webViewWillBeClosedSaveHistory(key: String) {
        let history = HistoryStorage.shared.getHistoryFromUserDefaults()![key]!
        let currentPosition = historyCurrentPosition + 1
        guard currentPosition != history.count else { return }
        removeUnusedPeaceOfHistory(key: key)
    }
}