Question

有人可以向我解释一下iOS应用程序上的文档目录以及何时使用它？

以下是我目前的看法：

对我而言，它似乎是一个中央文件夹，用户可以在其中存储应用程序所需的任何文件。

这与Core Data存储数据的位置不同？

似乎每个应用都有自己的文档目录。

我可以自由创建文档目录的子目录，如文档目录/图像，或文档目录/视频？

Answer 1

您的应用程序（在非越狱设备上）在“沙盒”环境中运行。这意味着它只能访问自己内容中的文件和目录。例如文档和库。

请参阅iOS Application Programming Guide。

要访问应用程序沙箱的文档目录，您可以使用以下命令：

iOS 8及更新版本，这是推荐的方法

+ (NSURL *)applicationDocumentsDirectory
{
     return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}

如果您需要支持iOS 7或更早版本

+ (NSString *) applicationDocumentsDirectory 
{    
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *basePath = paths.firstObject;
    return basePath;
}

此文档目录允许您存储应用创建或可能需要的文件和子目录。

要访问应用沙箱使用的库目录中的文件（代替上面的paths）：

[NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) objectAtIndex:0]

Answer 2

在iOS 8中已更改。请参阅以下技术说明：https://developer.apple.com/library/ios/technotes/tn2406/_index.html

Apple批准的方式（来自上面的链接）如下：

// Returns the URL to the application's Documents directory.
- (NSURL *)applicationDocumentsDirectory
{
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}

Answer 3

我找不到接受答案建议的文档中的代码，但我在此处找到了更新的等效文件：

<强> File System Programming Guide :: Accessing Files and Directories »

- (NSURL*)applicationDataDirectory {
    NSFileManager* sharedFM = [NSFileManager defaultManager];
    NSArray* possibleURLs = [sharedFM URLsForDirectory:NSApplicationSupportDirectory
                                 inDomains:NSUserDomainMask];
    NSURL* appSupportDir = nil;
    NSURL* appDirectory = nil;

    if ([possibleURLs count] >= 1) {
        // Use the first directory (if multiple are returned)
        appSupportDir = [possibleURLs objectAtIndex:0];
    }

    // If a valid app support directory exists, add the
    // app's bundle ID to it to specify the final directory.
    if (appSupportDir) {
        NSString* appBundleID = [[NSBundle mainBundle] bundleIdentifier];
        appDirectory = [appSupportDir URLByAppendingPathComponent:appBundleID];
    }

    return appDirectory;
}

它不鼓励使用NSSearchPathForDirectoriesInDomain：

NSSearchPathForDirectoriesInDomains函数的行为类似于 URLForDirectory：inDomains：方法但返回目录位置作为基于字符串的路径。你应该使用 URLForDirectory：inDomains：方法。

以下是一些其他有用的目录常量。毫无疑问，iOS中并不支持所有这些功能。您还可以使用NSHomeDirectory（）函数：

在iOS中，主目录是应用程序的沙箱目录。在OS X中，它是应用程序的沙箱目录或当前用户的主目录（如果应用程序不在沙箱中）

来自NSPathUtilities.h

NSApplicationDirectory = 1,             // supported applications (Applications)
    NSDemoApplicationDirectory,             // unsupported applications, demonstration versions (Demos)
    NSDeveloperApplicationDirectory,        // developer applications (Developer/Applications). DEPRECATED - there is no one single Developer directory.
    NSAdminApplicationDirectory,            // system and network administration applications (Administration)
    NSLibraryDirectory,                     // various documentation, support, and configuration files, resources (Library)
    NSDeveloperDirectory,                   // developer resources (Developer) DEPRECATED - there is no one single Developer directory.
    NSUserDirectory,                        // user home directories (Users)
    NSDocumentationDirectory,               // documentation (Documentation)
    NSDocumentDirectory,                    // documents (Documents)
    NSCoreServiceDirectory,                 // location of CoreServices directory (System/Library/CoreServices)
    NSAutosavedInformationDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 11,   // location of autosaved documents (Documents/Autosaved)
    NSDesktopDirectory = 12,                // location of user's desktop
    NSCachesDirectory = 13,                 // location of discardable cache files (Library/Caches)
    NSApplicationSupportDirectory = 14,     // location of application support files (plug-ins, etc) (Library/Application Support)
    NSDownloadsDirectory NS_ENUM_AVAILABLE(10_5, 2_0) = 15,              // location of the user's "Downloads" directory
    NSInputMethodsDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 16,           // input methods (Library/Input Methods)
    NSMoviesDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 17,                 // location of user's Movies directory (~/Movies)
    NSMusicDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 18,                  // location of user's Music directory (~/Music)
    NSPicturesDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 19,               // location of user's Pictures directory (~/Pictures)
    NSPrinterDescriptionDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 20,     // location of system's PPDs directory (Library/Printers/PPDs)
    NSSharedPublicDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 21,           // location of user's Public sharing directory (~/Public)
    NSPreferencePanesDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 22,        // location of the PreferencePanes directory for use with System Preferences (Library/PreferencePanes)
    NSApplicationScriptsDirectory NS_ENUM_AVAILABLE(10_8, NA) = 23,      // location of the user scripts folder for the calling application (~/Library/Application Scripts/code-signing-id)
    NSItemReplacementDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 99,       // For use with NSFileManager's URLForDirectory:inDomain:appropriateForURL:create:error:
    NSAllApplicationsDirectory = 100,       // all directories where applications can occur
    NSAllLibrariesDirectory = 101,          // all directories where resources can occur
    NSTrashDirectory NS_ENUM_AVAILABLE(10_8, NA) = 102                   // location of Trash directory

最后，NSURL类别中的一些便利方法 http://club15cc.com/code/ios/easy-ios-file-directory-paths-with-this-handy-nsurl-category

Answer 4

Swift 3和4作为全局var：

var documentsDirectory: URL {
    return FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).last!
}

作为FileManager扩展名：

extension FileManager {
    static var documentsDirectory: URL {
        return `default`.urls(for: .documentDirectory, in: .userDomainMask).last!
    }

    var documentsDirectory: URL {
        return urls(for: .documentDirectory, in: .userDomainMask).last!
    }
}

Answer 5

除Documents文件夹外，iOS还允许您将文件保存到temp和Library文件夹。

有关使用哪一个的更多信息，请参阅文档中的此链接：

“Where You Should Put Your App’s Files.”

Answer 6

为这种笨拙的调用添加一个扩展到FileManager可能更干净，如果没有别的话，整洁。类似的东西：

extension FileManager {
    static var documentDir : URL {
        return FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
    }
}

Answer 7

您可以使用此代码访问文档目录，它基本上用于以plist格式存储文件：

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths firstObject];
return documentsDirectory;

Answer 8

这是一个有用的小功能，可以更轻松地使用/创建iOS文件夹。

您将其传递给子文件夹的名称，它会将完整路径返回给您，并确保该目录存在。

（就个人而言，我在我的AppDelete类中坚持使用这个静态函数，但也许这不是最聪明的地方。）

以下是调用它的方法，以获取MySavedImages子目录的“完整路径”：

NSString* fullPath = [AppDelegate getFullPath:@"MySavedImages"];

这是完整的功能：

+(NSString*)getFullPath:(NSString*)folderName
{
    //  Check whether a subdirectory exists in our sandboxed Documents directory.
    //  Returns the full path of the directory.
    //
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    if (paths.count < 1)
        return nil;

    NSString *rootFolder = [paths firstObject];
    NSString* fullFolderPath = [rootFolder stringByAppendingPathComponent:folderName];

    BOOL isDirectory;
    NSFileManager* manager = [NSFileManager defaultManager];

    if (![manager fileExistsAtPath:fullFolderPath isDirectory:&isDirectory] || !isDirectory) {
        NSError *error = nil;
        NSDictionary *attr = [NSDictionary dictionaryWithObject:NSFileProtectionComplete
                                                         forKey:NSFileProtectionKey];
        [manager createDirectoryAtPath:fullFolderPath
           withIntermediateDirectories:YES
                            attributes:attr
                                 error:&error];
        if (error) {
            NSLog(@"Error creating directory path: %@", [error localizedDescription]);
            return nil;
        }
    }
    return fullFolderPath;
}

使用这个小函数，可以很容易地在应用程序的Documents目录中创建一个目录（如果它还不存在），并将文件写入其中。

以下是我将如何创建目录，并将其中一个图像文件的内容写入其中：

//  Let's create a "MySavedImages" subdirectory (if it doesn't already exist)
NSString* fullPath = [AppDelegate getFullPath:@"MySavedImages"];

//  As an example, let's load the data in one of my images files
NSString* imageFilename = @"icnCross.png";

UIImage* image = [UIImage imageNamed:imageFilename];
NSData *imageData = UIImagePNGRepresentation(image);

//  Obtain the full path+filename where we can write this .png to, in our new MySavedImages directory
NSString* imageFilePathname = [fullPath stringByAppendingPathComponent:imageFilename];

//  Write the data
[imageData writeToFile:imageFilePathname atomically:YES];

希望这有帮助！

Answer 9

与其他提到的一样，您的应用程序在沙盒环境中运行，您可以使用documents目录存储图像或应用程序可能使用的其他资产。根据用户的喜好下载脱机d文件-File System Basics - Apple Documentation - Which directory to use, for storing application specific files

已更新为Swift 5，您可以根据要求使用以下功能之一-

func getDocumentsDirectory() -> URL {
    let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
    return paths[0]
}

func getCacheDirectory() -> URL {
        let paths = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)
        return paths[0]
    }

func getApplicationSupportDirectory() -> URL {
        let paths = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)
        return paths[0]
    }

用法：

let urlPath = "https://jumpcloud.com/wp-content/uploads/2017/06/SSH-Keys.png" //Or string path to some URL of valid image, for eg.

if let url = URL(string: urlPath){
    let destination = getDocumentsDirectory().appendingPathComponent(url.lastPathComponent)
    do {
        let data = try Data(contentsOf: url) //Synchronous call, just as an example
        try data.write(to: destination)
    } catch _ {
        //Do something to handle the error
    }
}

什么是文件目录（NSDocumentDirectory）？

9 个答案:

iOS 8及更新版本，这是推荐的方法

如果您需要支持iOS 7或更早版本