在iOS应用中，有/Library/Application Support个文件夹（使用NSApplicationSupportDirectory访问）。我在那里保存用户下载的内容。内容就像补丁文件，为我的应用程序添加新的图像和数据。我希望它能够在应用更新中持续存在。我不要想要备份这些文件。
我不确定从NSPathUtilities.h这个巨大的列表中使用哪个。我的候选人是NSApplicationSupportDirectory和NSDownloadsDirectory。无法判断它们是否会以不同的方式持续存在。
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