Clearing "may not respond" warnings for UIView and UIViewController

In an iPad app, I'm using a custom subclass of UIView with UIViewController. Here's the view header:

@interface pdfView : UIView {
    CGPDFDocumentRef doc;
}

-(void)setDoc:(CGPDFDocumentRef)newDoc;

@end

And here's the controller header:

@interface iPadPDFTestViewController : UIViewController {
    CGPDFDocumentRef doc;
}

- (void)loadPDF;

@end

Part of the controller implementation:

- (void)viewDidLoad {
    [super viewDidLoad];
    [self loadPDF];
    [self.view setDoc:doc];
}

In Interface Builder, I've set the view object to use the class pdfView.

At compilation, [self.view setDoc:doc]; gives the warning "'UIView' may not respond to '--setDoc'." I'm guessing that this warning appears because the compiler thinks it's looking at UIView (which does not implement the s开发者_JAVA百科etDoc method) instead of pdfView. But why does it think that? And how can I tell it what class it's really looking at, so as to clear the warning?

The compiler only knows what the code defines, and a UIViewController defines it's view property as a UIView, which is why you're seeing warnings.

You can avoid warnings by casting the view to your PDFView: (PDFView *)self.view;

To make this simpler implement a basic getter method

- (PDFView *)view {
    return (PDFView *)self.view;
}

Also, just as a side note, you should really name your classes so they start with atleast one uppercase char, and ideally a prefix (i.e. PDFView, ideally MYPDFView (where MY is a custom prefix)).