Creating a simple pdf

I'm trying to create a PDF on the iPhone for practice. I'm not sure why it doesn't work. I get the error:

2011-09-21 21:35:00.412 CreatePDF[869:b303] -[CreatePDFViewController createPDFDocumentAtURL:]
CreatePDF[869] <Error>: CGDataConsumerCreateWithFilename: failed to open `/Users/jon/Library/Application Support/iPhone Si开发者_开发知识库mulator/4.3.2/Applications/4486CF27-B309-4C7C-82A5-B425B9E2C04D/Documents' for writing: Is a directory.
deflateEnd: error -3: (null).
CreatePDF[869] <Error>: CGPDFContextCreate: failed to create PDF context delegate.
2011-09-21 21:35:00.419 CreatePDF[869:b303] Couldn't create PDF context
<Error>: CGContextBeginPage: invalid context 0x0

Here is the code I have:

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSURL *documentsURL = [NSURL fileURLWithPath:documentsDirectory];
    [self createPDFDocumentAtURL:(CFURLRef)documentsURL];
    NSLog(@"%s", __FUNCTION__);
}


- (void)createPDFDocumentAtURL:(CFURLRef)url {
    NSLog(@"%s", __FUNCTION__);
    float red[] = {1., 0., 0., 1. };
    CGRect mediaBox = CGRectMake(0, 0, 850, 1100);
    CGContextRef pdfContext = CGPDFContextCreateWithURL(url, &mediaBox, NULL);
    if (!pdfContext) {
        NSLog(@"Couldn't create PDF context");
    }
    CGContextBeginPage(pdfContext, &mediaBox);
    CGContextSaveGState(pdfContext);
    CGContextClipToRect(pdfContext, mediaBox);
    CGContextSetFillColorSpace(pdfContext, CGColorSpaceCreateDeviceRGB());
    CGContextSetFillColor(pdfContext, red);
    CGContextFillRect(pdfContext, mediaBox);
    CGContextRestoreGState(pdfContext);
    CGContextEndPage(pdfContext);
    CGContextRelease(pdfContext);
}

You have to add the new file's name to your URL. Your documentsURL contains this right now:

/Users/jon/Library/Application Support/iPhone Simulator/4.3.2/Applications/4486CF27-B309-4C7C-82A5-B425B9E2C04D/Documents/