Retired Document
Important: This document is replaced by File System Programming Guide.
Resolving Aliases
Unlike symbolic links, Mac OS X aliases are not handled automatically by Cocoa. This article explains how to resolve aliases in a path.
Paths returned by Cocoa classes such as NSOpenPanel
may contain alias references that you must resolve before using. To resolve aliases in a path contained in an NSString
, you need to first convert the string to a URL, convert the URL to an FSRef, resolve the alias, and reverse the series of conversions to yield another NSString
. To perform the necessary conversions, you need to use the URL and alias services provided in <CoreServices/CoreServices.h>
. The following code fragment uses FSResolveAliasFile
to resolve any aliases in path
and stores the resolved path in resolvedPath
:
NSString *path = <#Get a suitable path#>; |
NSString *resolvedPath = nil; |
CFURLRef url = CFURLCreateWithFileSystemPath |
(kCFAllocatorDefault, (CFStringRef)path, kCFURLPOSIXPathStyle, NO); |
if (url != NULL) |
{ |
FSRef fsRef; |
if (CFURLGetFSRef(url, &fsRef)) |
{ |
Boolean targetIsFolder, wasAliased; |
OSErr err = FSResolveAliasFile (&fsRef, true, &targetIsFolder, &wasAliased); |
if ((err == noErr) && wasAliased) |
{ |
CFURLRef resolvedUrl = CFURLCreateFromFSRef(kCFAllocatorDefault, &fsRef); |
if (resolvedUrl != NULL) |
{ |
resolvedPath = (NSString*) |
CFURLCopyFileSystemPath(resolvedUrl, kCFURLPOSIXPathStyle); |
CFRelease(resolvedUrl); |
} |
} |
} |
CFRelease(url); |
} |
if (resolvedPath == nil) |
{ |
resolvedPath = [[NSString alloc] initWithString:path]; |
} |
The second argument to FSResolveAliasFile
specifies whether you want the function to resolve all aliases in a chain (for example, an alias file that refers to an alias file and so on), stopping only when it reaches the target file.
Copyright © 1997, 2011 Apple Inc. All Rights Reserved. Terms of Use | Privacy Policy | Updated: 2011-05-25