Question

Hi I am recently work with Leaves api and I have problem with this , I need to display a PDF file , and my ViewController class has a nib file , I implement the code base on API sample code but does not show anything ! Am I missing something ?

#import "BookViewController.h"
#import "Utilities.h"

@implementation BookViewController



/////EDITED//////////////


- (id) initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{
    if (self = [super initWithNibName:@"BookViewController" bundle:nil]) {

        CFURLRef pdfURL = CFBundleCopyResourceURL(CFBundleGetMainBundle(), CFSTR("paper.pdf"), NULL, NULL);
        pdf = CGPDFDocumentCreateWithURL((CFURLRef)pdfURL);
        CFRelease(pdfURL);

    }
    return self;
}





- (void)dealloc {
    CGPDFDocumentRelease(pdf);
    [super dealloc];
}



- (void) displayPageNumber:(NSUInteger)pageNumber {
    self.navigationItem.title = [NSString stringWithFormat:
                                 @"Page %u of %u", 
                                 pageNumber, 
                                 CGPDFDocumentGetNumberOfPages(pdf)];
}



#pragma mark  LeavesViewDelegate methods

- (void) leavesView:(LeavesView *)leavesView willTurnToPageAtIndex:(NSUInteger)pageIndex {
    [self displayPageNumber:pageIndex + 1];
}



#pragma mark LeavesViewDataSource methods

- (NSUInteger) numberOfPagesInLeavesView:(LeavesView*)leavesView {
    return CGPDFDocumentGetNumberOfPages(pdf);
}

- (void) renderPageAtIndex:(NSUInteger)index inContext:(CGContextRef)ctx {
    CGPDFPageRef page = CGPDFDocumentGetPage(pdf, index + 1);
    CGAffineTransform transform = aspectFit(CGPDFPageGetBoxRect(page, kCGPDFMediaBox),
                                            CGContextGetClipBoundingBox(ctx));
    CGContextConcatCTM(ctx, transform);
    CGContextDrawPDFPage(ctx, page);
}


#pragma mark UIViewController

- (void) viewDidLoad {
    [super viewDidLoad];
    leavesView.backgroundRendering = YES;
    [self displayPageNumber:1];
}

Answer 1

How are you instantiating your controller?

If you call initWithNibName (as I suppose you do, since you say it has a nib file), you are totally skipping your local init method (i.e., the one in BookController); therefore, the PDF handling is not initialized at all.

Try renaming your init method to initWithNibName, and it should work; or create an initWithNibName and make it call you init (google for “designated constructor” to learn more about this pattern).

Notice that the full signature of initWithNibName is:

- (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)nibBundle

You have more options available, like creating the controller by calling init (instead of initWithNibName) or even create a method setPDF, then, after you create the controller any way you like, you can call this method, which in turns calls initialize, etc…

EDIT: if you decide to instantiate manually the controller, don’t forget to define loadView:

- (void)loadView {
    [super loadView];
    if (leavesView) {
        leavesView.frame = self.view.bounds;
        leavesView.autoresizingMask = UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
        [self.view addSubview:leavesView];
    }
}