Save files avoiding duplicate filenames and overwriting - objective-c

Question

So, here's my situation :
I've got an application prompting the user to select a folder to save his files
Now let's say his files are : a.png, b.png, c.png
What I want is :
if file - let's say - a.png already exists in the selected folder, DON'T overwrite it. Instead create a file with name a (1).png. If a file a (1).png already exists, then name it like a (2).png, and so on - pretty much like OS X does when copy-pasting files with the same name.
This is how I'm currently doing it - but it still doesn't strike me ok :
NSString* target = [self getTargetPathForFile:filename path:folder];
NSString* fname = [target lastPathComponent];
while ([[NSFileManager defaultManager] fileExistsAtPath: [folder stringByAppendingPathComponent:fname]])
{
//NSLog(#"FNAME : %#",fname);
if ([self str:fname containsString:#")." options:nil])
{
NSArray* a = [fname componentsSeparatedByString:#"("];
NSArray* b = [[a objectAtIndex:1] componentsSeparatedByString:#")"];
fname = [NSString stringWithFormat:#"%#(%d)%#",[a objectAtIndex:0],[[b objectAtIndex:0] intValue]+1,[b objectAtIndex:1]];
}
else
{
fname = [NSString stringWithFormat:#"%# (1).%#",[fname stringByDeletingPathExtension],[fname pathExtension]];
}
//NSLog(#"Setting filename to :: %#",fname);
}
target = [folder stringByAppendingPathComponent:fname];
Any ideas how to go about this? Is there any Cocoa-friendly (or built-in) method for this?

Answer 1

Why not try this one :
NSString* fname = [target lastPathComponent];
NSString* fnameNoExt = [fname stringByDeletingPathExtension];
NSString* extension = [fname pathExtension];
int fileIndex = 1;
while ([[NSFileManager defaultManager] fileExistsAtPath: [folder stringByAppendingPathComponent:fname]])
{
//NSLog(#"FNAME : %#",fname);
fname = [NSString stringWithFormat:#"%# (%d).%#", fnameNoExt, fileIndex, extension];
//NSLog(#"Setting filename to :: %#",fname);
fileIndex++;
}
target = [folder stringByAppendingPathComponent:fname];

Answer 2

If you don't really care about the file names as you explained in one of your comment, and can consider using automatically-generated file names instead, use either CFUUID, NSProcessInfo, or mkstemp.
Using CFUUID to generate a unique identifier str:
CFUUIDRef uuidref = CFUUIDCreate(NULL);
CFStringRef cfstr = CFUUIDCreateString(NULL, uuidref);
// If using ARC:
NSString* filename = (__bridge_transfer NSString*)cfstr;
// If not using ARC
NSString* filename = [(NSString*)cfstr autorelease];
// Then release the CFUUIDRef
CFRelease(uuidref);
Using NSProcessInfo
NSString* filename = [[NSProcessInfo processInfo] globallyUniqueString];
Using mkstemp: see CocoaWithLove