NSFileManager unique file names

Question

I need a quick and easy way to store files with unique file names on iOS. I need to prefix the file with a string, and then append the generated unique identifier to the en

Answer 1

This should probably work for you:

http://vgable.com/blog/2008/02/24/creating-a-uuid-guid-in-cocoa/

The author of the post suggests implementing a 'stringWithUUID' method as a category of NSString. Just append a GUID generated with this method to the end of the file name that you're creating.

Answer 2

Super-easy Swift 4 1-liner:

fileName = "MyFileName_" + UUID().uuidString

or

fileName = "MyFileName_" + ProcessInfo().globallyUniqueString

Answer 3

Create your own file name:

CFUUIDRef uuid = CFUUIDCreate(NULL);
CFStringRef uuidString = CFUUIDCreateString(NULL, uuid);
CFRelease(uuid);
NSString *uniqueFileName = [NSString stringWithFormat:@"%@%@", prefixString, (NSString *)uuidString];
CFRelease(uuidString);

A simpler alternative proposed by @darrinm in the comments:

NSString *prefixString = @"MyFilename";

NSString *guid = [[NSProcessInfo processInfo] globallyUniqueString] ;
NSString *uniqueFileName = [NSString stringWithFormat:@"%@_%@", prefixString, guid];

NSLog(@"uniqueFileName: '%@'", uniqueFileName);

NSLog output:
uniqueFileName: 'MyFilename_680E77F2-20B8-444E-875B-11453B06606E-688-00000145B460AF51'

Note: iOS6 introduced the NSUUID class which can be used in place of CFUUID.

NSString *guid = [[NSUUID new] UUIDString];