A simple class wrapping a movable file/folder location using Aliases.

Location.m

#import <Foundation/Foundation.h>
#import <CoreServices/CoreServices.h>

@interface Location
{
    FSRef        fsRef;
    HFSUniStr255 name;
}

@property (readonly) FSRef * fileRef;
@property (readonly) NSString * path;
@property (readonly) NSData * aliasData;

+ (Location *) locationWithFSRef: (FSRef *) ref;
+ (Location *) locationWithAliasData: (NSData *) aliasData;

- (id) initWithFSRef: (FSRef *) ref;
- (id) initWithAliasData: (NSData *) aliasData;

@end

@implementation Location

- (id) initWithFSRef: (FSRef *) ref
{
    if ( [super init] == nil )
        return ( nil );
    
    memcpy( &fsRef, ref, sizeof(FSRef) );
    
    return ( self );
}

- (id) initWithAliasData: (NSData *) aliasData
{
    if ( [super init] == nil )
        return ( nil );
    
    AliasHandle aliasHandle = (AliasHandle) NewHandle( (Size) [aliasData length] );
    PtrToHand( [aliasData bytes], aliasHandle, [aliasData length] );
    
    Boolean wasChanged = FALSE;
    OSErr err = FSResolveAlias( NULL, aliasHandle, &fsRef, &wasChanged );
    
    DisposeHandle( (Handle) aliasHandle );
    
    if ( err != noErr )
    {
        [self release];
        return ( nil );
    }
    
    return ( self );
}

- (id) initWithCoder: (NSCoder *) coder
{
    if ( [super init] == nil )
        return ( nil );
    
    NSData * aliasData = nil;
    if ( [coder allowsKeyedCoding] )
        aliasData = [coder decodeObjectForKey: @"aliasData"];
    else
        aliasData = [coder decodeObject];
    
    AliasHandle aliasHandle = (AliasHandle) NewHandle( (Size) [aliasData length] );
    PtrToHand( [aliasData bytes], aliasHandle, [aliasData length] );
    
    Boolean wasChanged = FALSE;
    OSErr err = FSResolveAlias( NULL, aliasHandle, &fsRef, &wasChanged );
    
    DisposeHandle( (Handle) aliasHandle );
	
    if ( err != noErr )
    {
        [self autorelease];
        return ( nil );
    }
    
    return ( self );
}

- (void) encodeWithCoder: (NSCoder *) coder
{
    if ( [coder allowsKeyedCoding] )
        [coder encodeObject: self.aliasData forKey: @"aliasData"];
    else
        [coder encodeObject: self.aliasData];
}

- (id) copyWithZone: (NSZone *) zone
{
    // only need to copy the FSRef
    return ( [[MFLocation alloc] initWithFSRef: &fsRef] );
}

- (void) isEqual: (MFLocation *) other
{
    return ( FSCompareFSRefs(&fsRef, &other->fsRef) == noErr );
}

- (FSRef *) fileRef
{
    return ( &fsRef );
}

- (NSString *) path
{
    char buffer[PATH_MAX+1];
    if ( FSRefMakePath(&fsRef, (UInt8 *) buffer, PATH_MAX+1) != noErr )
        return ( nil );
    
    return ( [NSString stringWithUTF8String: buffer] );
}

- (NSData *) aliasData
{
    AliasHandle alias = NULL;
    if ( FSNewAliasMinimal(&fsRef, &alias) != noErr )
    	return ( nil );
    
    HLock( (Handle) alias );
    NSData * result = [NSData dataWithBytes: (void *)(*alias) length: GetAliasSize(alias)];
    HUnlock( (Handle) alias );
    DisposeHandle( (Handle) alias );
    
    return ( result );
}

@end