UIManagedDocument saveToURL always returns false - iphone

Question

I'm trying to create a UIManagedDocument that doesn't yet exists. Here is my code:
url = [NSURL URLWithString:#"file://ProjectSSDB"];
document = [[UIManagedDocument alloc] initWithFileURL:url];
if ([[NSFileManager defaultManager] fileExistsAtPath:[url path]]) {
[document openWithCompletionHandler: ^(BOOL success) {
if (success) [ProjectSSViewController documentIsReady];
if (!success) NSLog(#"Couldn't open document at %#", url);
}];
} else {
[document saveToURL:url forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
NSLog(#"Returned %d", success);
if (success) [ProjectSSViewController documentIsReady];
if (!success) NSLog(#"Couldn't create document at %#", url);
}];
}
My problem is that the file doesn't exist yet, and the saveToURL operation always seems to be returning false. Is there anyway I can debug this further as to why this is happening?
EDIT:
Ok, so I can't write to that URL. I've now tried doing this:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSURL *url = [NSURL URLWithString:documentsDirectory];
NSLog(#"The URL is %#", [url absoluteString]);
When it runs, the log seems to return that the URL is null. Is there something else that I'm doing wrong?

Answer 1

You can't write at this path "file://ProjectSSDB", you don't have the permission, you need to get the root of your application in this way:
NSString* rootPath = NSHomeDirectory();
and save the the data in one of the sub folder as specified by Apple file system guide line
NSString* fullPath = [rootPath stringByAppendingPathComponent:#"subFoldeder/file.extension"];

Answer 2

I've been successfully using following code snippet for generating UIManagedDocument's URL for quite a while:
NSURL *url = [NSFileManager.defaultManager URLsForDirectory:NSLibraryDirectory inDomains:NSUserDomainMask].firstObject;
url = [url URLByAppendingPathComponent:#"ARBITRARY_NAME"];
self.document = [UIManagedDocument.alloc initWithFileURL:url];
P.s.: it's iOS 5+ solution.
Let me know if that works for you ;)