UIDocumentInteractionController nil string parameter

Question

I am using UIDocumentInteractionController to display images, recordings, videos, etc. in this way:

NSURL *URL = [[NSBundle mainBundle] URLForResource:@"2013-08-01 13_20_44 (id)" withExtension:@"mov"];

OR

NSData* dataFile = [dict objectForKey:@"FileData"];
    NSString *urlString = [[NSString alloc] initWithData:dataFile encoding:NSUTF8StringEncoding]; // Or any other appropriate encoding
    NSURL *URL = [[NSURL alloc] initWithString:urlString];

Then:

if (URL) {
        // Initialize Document Interaction Controller
        documentInteractionController = [UIDocumentInteractionController interactionControllerWithURL:URL];

        // Configure Document Interaction Controller
        [documentInteractionController setDelegate:self];

        // Preview PDF
        [documentInteractionController presentPreviewAnimated:YES];
    }

By accessing the document from the mainBundle, sometimes it works, sometimes instead I get the following error:

2014-05-23 12:25:54.648 Cleverly[362:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL initWithString:relativeToURL:]: nil string parameter'

With the NSData way, I always get it (the NSData is not corrupt, I can open it fine in other ways).

1) Why is this? 2) How can I prevent it at least from crashing? 3) What does the error mean? (why it works for some resources in the mainBundle and not others)?

Thanks in advance for any help

Answer 1

as crash stated, there might be some cases in the logic which are returning nil urlString, To avoid the crash please add following condition:

if(nil != urlString)
{
    NSURL *URL = [[NSURL alloc] initWithString:urlString];
}

or find the root cause which is returning invalid urlString.