gistfile1.m

This was nice and fast... but it takes up WAY TOO MUCH space. And it's annoying to write.
(I like the way I can just step into the function that calls the delegate for debugging)

What's a better way to not make me call respondsToSelector in the middle of my code? Some proxy?

    struct {
        unsigned int delegateWillDisplayDocument:1;
        unsigned int delegateDidDisplayDocument:1;
        unsigned int delegateDidShowPageView:1;
        unsigned int delegateDidRenderPageView:1;
        unsigned int delegateDidChangeViewMode:1;
        unsigned int delegateDidTapOnPageView:1;
        unsigned int delegateDidTapOnAnnotation:1;
        unsigned int delegateShouldDisplayAnnotation:1;
        unsigned int delegateViewForAnnotation:1;        
        unsigned int delegateAnnotationViewForAnnotation:1;
        unsigned int delegateWillShowAnnotationView:1;
        unsigned int delegateDidShowAnnotationView:1;
        unsigned int delegateDidLoadPageView:1;
        unsigned int delegateWillUnloadPageView:1;
        unsigned int delegateDidEndPageScrollingAnimation:1;
        unsigned int delegateDidEndZoomingAtScale:1;
        unsigned int delegateWillShowControllerAnimated:1;
        unsigned int delegateDidShowControllerAnimated:1;
    } delegateFlags_;

- (void)setDelegate:(id<PSPDFViewControllerDelegate>)delegate {
    if (delegate != delegate_) {
        delegate_ = delegate;
        delegateFlags_.delegateWillDisplayDocument = [delegate respondsToSelector:@selector(pdfViewController:willDisplayDocument:)];
        delegateFlags_.delegateDidDisplayDocument = [delegate respondsToSelector:@selector(pdfViewController:didDisplayDocument:)];
        delegateFlags_.delegateDidShowPageView = [delegate respondsToSelector:@selector(pdfViewController:didShowPageView:)];
        delegateFlags_.delegateDidRenderPageView = [delegate respondsToSelector:@selector(pdfViewController:didRenderPageView:)];
        delegateFlags_.delegateDidChangeViewMode = [delegate respondsToSelector:@selector(pdfViewController:didChangeViewMode:)];
        delegateFlags_.delegateDidTapOnPageView = [delegate respondsToSelector:@selector(pdfViewController:didTapOnPageView:info:coordinates:)];
        delegateFlags_.delegateDidTapOnAnnotation = [delegate respondsToSelector:@selector(pdfViewController:didTapOnAnnotation:page:info:coordinates:)];
        delegateFlags_.delegateShouldDisplayAnnotation = [delegate respondsToSelector:@selector(pdfViewController:shouldDisplayAnnotation:onPageView:)];
        delegateFlags_.delegateViewForAnnotation = [delegate respondsToSelector:@selector(pdfViewController:viewForAnnotation:onPageView:)];
        delegateFlags_.delegateAnnotationViewForAnnotation = [delegate respondsToSelector:@selector(pdfViewController:annotationView:forAnnotation:onPageView:)];
        delegateFlags_.delegateWillShowAnnotationView = [delegate respondsToSelector:@selector(pdfViewController:willShowAnnotationView:onPageView:)];
        delegateFlags_.delegateDidShowAnnotationView = [delegate respondsToSelector:@selector(pdfViewController:didShowAnnotationView:onPageView:)];
        delegateFlags_.delegateDidLoadPageView = [delegate respondsToSelector:@selector(pdfViewController:didLoadPageView:)];
        delegateFlags_.delegateWillUnloadPageView = [delegate respondsToSelector:@selector(pdfViewController:willUnloadPageView:)];
        delegateFlags_.delegateDidEndPageScrollingAnimation = [delegate respondsToSelector:@selector(pdfViewController:didEndPageScrollingAnimation:)];
        delegateFlags_.delegateDidEndZoomingAtScale = [delegate respondsToSelector:@selector(pdfViewController:didEndPageZooming:atScale:)];
        delegateFlags_.delegateWillShowControllerAnimated = [delegate respondsToSelector:@selector(pdfViewController:willShowController:embeddedInController:animated:)];
        delegateFlags_.delegateDidShowControllerAnimated = [delegate respondsToSelector:@selector(pdfViewController:didShowController:embeddedInController:animated:)];
    }
}

- (void)delegateWillDisplayDocument {
    if (delegateFlags_.delegateWillDisplayDocument) {
        [self.delegate pdfViewController:self willDisplayDocument:self.document];
    }
}

- (void)delegateDidDisplayDocument {
    if(delegateFlags_.delegateDidDisplayDocument) {
        [self.delegate pdfViewController:self didDisplayDocument:self.document];
    }
}

(etc, etc)

1. Like I said, you can't use -forwardingTargetForSelector:, because if nothing happens there, the runtime will try -forwardInvocation:.
2. The compound literal is so that you can build the struct in one pass, without having to set all of its values individually. So, the following are equivalent:

// this is retarded:
point.x = 1.f;
point.y = 3.f;

// this is awesome:
point = (CGPoint) { .x = 1.f, .y = 3.f };

a macro or a simple function or method would look good and could even use the caching (don't know If Id want that though)...

anyways :) id be interested in hearing what you finally decide on

I prefer to check the respondsToSelector in place. Generally rather dislike such caches. I usually don't have that much delegate methods though...

However, you could build a proxy class that assembles method implementations automatically using runtime calls. That'd be extremely elegant, albeit a bit of work and probably shooting with canons on pigeons. You could open-source it afterwards though ;)

No proxy tricks, but FWIW I use ids directly:

struct
{
    id willDisplayDocumentDelegate;
    id didDisplayDocumentDelegate;
    // etc.
} _delegates;

- (void)setDelegate:(id <PSPDFViewControllerDelegate>)delegate
{
    if (delegate)
    {
        if ([delegate respondsToSelector:@selector(pdfViewController:willDisplayDocument:)])
            _delegates.willDisplayDocumentDelegate = delegate;

        if ([delegate respondsToSelector:@selector(pdfViewController:didDisplayDocument:)])
            _delegates.didDisplayDocumentDelegate = delegate;

        // etc.
    }
    else
        memset(_delegates, 0, sizeof(_delegates));
}

- (void)delegateWillDisplayDocument
{
    [_delegates.willDisplayDocumentDelegate pdfViewController:self willDisplayDocument:self.document];
}

- (void)delegateDidDisplayDocument
{
    [delegates_.didDisplayDocumentDelegate pdfViewController:self didDisplayDocument:self.document];
}

// etc.

I like your approach, @hatfinch, but should the zeroing of the _delegates table not should happen first, and unconditionally, as the if statements only set the fields for methods that are present in the new delegate. If there was a previous setting for a field and the new delegate doesn't implement that method, the old value would still be present (causing the old delegate to be called for some methods).

Also, I believe that object refs in a struct are no longer allowed under ARC, but (__weak) ivars could work just as well.