iOS - FileManager 扩展的最佳实践

Posted 2023-03-07

【中文标题】iOS - FileManager 扩展的最佳实践

【英文标题】：iOS - Best practices for FileManager extensions

【发布时间】：2017-01-13 21:37:12

【问题描述】：

我创建了这个FileManager extension。有了这个extension，我想创建一个像这样的文件层次结构：

应用支持 收藏夹 饲料 图片

这是我在FileManagerextension 中的代码，我会在应用启动后立即调用app delegate。然后我将使用此代码始终检索文件夹的path。

这是创建此层次结构并在需要时检索路径的好方法吗？这是好习惯吗？

extension FileManager 
    static func createOrFindApplicationDirectory() -> URL? 
        let bundleID = Bundle.main.bundleIdentifier
        // Find the application support directory in the home directory.
        let appSupportDir = self.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)

        guard appSupportDir.count > 0 else 
            return nil
        

        // Append the bundle ID to the URL for the Application Support directory.
        let dirPath = appSupportDir[0].appendingPathComponent(bundleID!)

        // If the directory does not exist, this method creates it.
        do 
            try self.default.createDirectory(at: dirPath, withIntermediateDirectories: true, attributes: nil)
            return dirPath
         catch let error 
            print("Error creating Application Support directory with error: \(error)")
            return nil
        
    

    static func createOrFindFavoritesDirectory() -> URL? 
        guard let appSupportDir = createOrFindApplicationDirectory() else 
            return nil
        

        let dirPath = appSupportDir.appendingPathComponent("Favorites")

        // If the directory does not exist, this method creates it.
        do 
            try self.default.createDirectory(at: dirPath, withIntermediateDirectories: true, attributes: nil)
            return dirPath
         catch let error 
            print("Error creating Favorites directory with error: \(error)")
            return nil
        
    

    static func createOrFindFeedDirectory() -> URL? 
        guard let appSupportDir = createOrFindFavoritesDirectory() else 
            return nil
        

        let dirPath = appSupportDir.appendingPathComponent("Feed")

        // If the directory does not exist, this method creates it.
        do 
            try self.default.createDirectory(at: dirPath, withIntermediateDirectories: true, attributes: nil)
            return dirPath
         catch let error 
            print("Error creating Favorites directory with error: \(error)")
            return nil
        
    

    static func currentImagesDirectory() -> URL? 
        guard let feedDir = createOrFindFeedDirectory() else 
            return nil
        

        let dirPath = feedDir.appendingPathComponent("Images")

        // If the directory does not exist, this method creates it.
        do 
            try self.default.createDirectory(at: dirPath, withIntermediateDirectories: true, attributes: nil)
            return dirPath
         catch let error 
            print("Error creating Images directory with error: \(error)")
            return nil
        
    

【问题讨论】：

我觉得不错。

@ILikeTau 谢谢！你有什么不同的做法吗？我希望看到其他一些示例，无论是您自己的代码还是与我正在尝试做的事情类似的教程/链接。

我可能会将createOrFindFavoritesDirectory() 和createOrFindFeedDirectory() 组合成一个带参数的函数，但除此之外，它看起来都很好。

@ILikeTau 你能发布一个答案吗？我只是很想知道其他人会如何做到这一点——尝试向比我更好的人学习:)

【参考方案1】：

看起来不错，但你可以结合一些代码并进行更好的错误检查：

extension FileManager 
    static func createOrFindApplicationDirectory() -> URL? 
        guard let bundleID = Bundle.main.bundleIdentifier else 
            return nil
        

        // Find the application support directory in the home directory.
        let appSupportDirArray = self.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)

        guard let appSupportDir = appSupportDirArray.first else 
            return nil
        

        // Append the bundle ID to the URL for the Application Support directory.
        let dirPath = appSupportDir.appendingPathComponent(bundleID)

        // If the directory does not exist, this method creates it.
        do 
            try self.default.createDirectory(at: dirPath, withIntermediateDirectories: true, attributes: nil)
            return dirPath
         catch let error 
            print("Error creating Application Support directory with error: \(error)")
            return nil
        
    

    static func createOrFindDirectory(named name: String) -> URL? 
        guard let appSupportDir = createOrFindApplicationDirectory() else 
            return nil
        

        let dirPath = appSupportDir.appendingPathComponent(name)

        // If the directory does not exist, this method creates it.
        do 
            try self.default.createDirectory(at: dirPath, withIntermediateDirectories: true, attributes: nil)
            return dirPath
         catch let error 
            print("Error creating \(name) directory with error: \(error)")
            return nil
        
    

    static func currentImagesDirectory() -> URL? 
        guard let feedDir = createOrFindDirectory(named: "Feed") else 
            return nil
        

        let dirPath = feedDir.appendingPathComponent("Images")

        // If the directory does not exist, this method creates it.
        do 
            try self.default.createDirectory(at: dirPath, withIntermediateDirectories: true, attributes: nil)
            return dirPath
         catch let error 
            print("Error creating Images directory with error: \(error)")
            return nil
        
    

【讨论】：

看起来不错！我看到您将 Feed 和收藏夹合并为一个功能 static func createOrFindDirectory(named name: String) -> URL?，很酷。就“错误检查”而言，我确实需要在首次启动应用程序时创建这些文件夹/目录。除了返回nil 之外，您如何处理错误，以便我保证这些文件夹是在继续之前创建的？关键是，如果没有在应用启动时创建这些文件夹，我的应用将无法正常运行

既然你提到了错误处理，这让我想了更多。我不确定“创建”这些文件夹之一可能会失败的确切时间，但如果确实如此，不知道如何处理它这样应用在创建之前不会继续进行