Rename iCloud Document

gistfile1.m

NSURL *sourceURL = document.fileURL;
NSURL *destinationURL = [[sourceURL URLByDeletingLastPathComponent] URLByAppendingPathComponent:fileName isDirectory:NO];
        
NSError *writeError = nil;
__block NSError *moveError = nil;
__block BOOL success = NO;
        
NSFileCoordinator *coordinator = [[NSFileCoordinator alloc] initWithFilePresenter:nil];
[coordinator coordinateWritingItemAtURL: sourceURL options: NSFileCoordinatorWritingForMoving writingItemAtURL: destinationURL options: NSFileCoordinatorWritingForReplacing error: &writeError byAccessor: ^(NSURL *newURL1, NSURL *newURL2) {
    NSFileManager *fileManager = [[NSFileManager alloc] init];
    success = [fileManager moveItemAtURL:newURL1 toURL:newURL2 error:&moveError];
    if (success) [coordinator itemAtURL:newURL1 didMoveToURL:newURL2];
}];