UIWebView zeigt leeren Bildschirm in iOS 8

Habe ich eine app, wo ich es herunterladen einer pdf-Datei und speichern Sie es in das iPhone. Es funktionierte perfekt in iOS 7 (ich bin derzeit mit iOS 8) und während der Ausführung der app in iOS 8, die webView einfach leer bleibt. Ich habe ich keine Idee, was falsch ist.

#import "ISJMMisalViewController.h"
#import "SWRevealViewController.h"

@implementation ISJMMisalViewController
@synthesize activityImageView;

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:YES];

    [self.webView addSubview:activityImageView];
    [activityImageView startAnimating];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        NSString *resourceDocPath = [[NSString alloc] initWithString:[[[[NSBundle mainBundle] resourcePath]stringByDeletingLastPathComponent] stringByAppendingPathComponent:@"Documents"]];
        NSString *filePath = [resourceDocPath stringByAppendingPathComponent:@"misalLocal.pdf"];

        //Now create Request for the file that was saved in your documents folder
        NSURL *url = [NSURL fileURLWithPath:filePath];
        NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];

        dispatch_async(dispatch_get_main_queue(), ^{

            [self.webView setUserInteractionEnabled:YES];
            [self.webView setDelegate:self];
            [self.webView loadRequest:requestObj];
            [self.webView setScalesPageToFit:YES];
            [activityImageView stopAnimating];
            [activityImageView removeFromSuperview];

        });
    });

}

- (void)viewDidLoad {
    [super viewDidLoad];

    [self.view addGestureRecognizer:self.revealViewController.panGestureRecognizer];

    UIImage *image = [UIImage imageNamed: @"NavBarImage.png"];
    UIImageView *imageView = [[UIImageView alloc] initWithImage: image];

    self.navigationItem.titleView = imageView;

    _sidebarButton.target = self.revealViewController;
    _sidebarButton.action = @selector(revealToggle:);

    //Create the first status image and the indicator view
    UIImage *statusImage = [UIImage imageNamed:@"1.png"];
    activityImageView = [[UIImageView alloc] initWithImage:statusImage];


    //Add more images which will be used for the animation
    activityImageView.animationImages = [NSArray arrayWithObjects:
                                         [UIImage imageNamed:@"1.png"],
                                         [UIImage imageNamed:@"2.png"],
                                         [UIImage imageNamed:@"3.png"],
                                         [UIImage imageNamed:@"4.png"],
                                         [UIImage imageNamed:@"5.png"],
                                         [UIImage imageNamed:@"6.png"],
                                         [UIImage imageNamed:@"7.png"],
                                         [UIImage imageNamed:@"8.png"],
                                         [UIImage imageNamed:@"9.png"],
                                         nil];


    //Set the duration of the animation (play with it
    //until it looks nice for you)
    activityImageView.animationDuration = 0.7;


    //Position the activity image view somewhere in
    //the middle of your current view
    activityImageView.frame = CGRectMake(self.view.frame.size.width/2 - 50, self.view.frame.size.height/2 - 100, 100, 100);

    UITapGestureRecognizer *gesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(toggleNavBar:)];
    [self. webView addGestureRecognizer:gesture];

    if (!self.webView) {

        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Sin conexión"
                                                        message:@"No fue posible la descarga de datos debido a que no se pudo conectar con el servidor"
                                                       delegate: nil
                                              cancelButtonTitle: @"OK"
                                              otherButtonTitles: nil];

        [alert show];

    }


}

- (IBAction)actualizar:(id)sender {

    [self.webView addSubview:activityImageView];
    [activityImageView startAnimating];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        NSData *pdfData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://isjm.weebly.com/uploads/2/5/3/6/25368636/misal.pdf"]];
        NSString *resourceDocPath = [[NSString alloc] initWithString:[[[[NSBundle mainBundle] resourcePath]stringByDeletingLastPathComponent] stringByAppendingPathComponent:@"Documents"]];
        NSString *filePath = [resourceDocPath stringByAppendingPathComponent:@"misalLocal.pdf"];
        [pdfData writeToFile:filePath atomically:YES];

        NSURL *url = [NSURL fileURLWithPath:filePath];
        NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];

        dispatch_async(dispatch_get_main_queue(), ^{

            [self.webView setUserInteractionEnabled:YES];
            [self.webView setDelegate:self];
            [self.webView loadRequest:requestObj];
            [self.webView setScalesPageToFit:YES];
            [activityImageView stopAnimating];
            [activityImageView removeFromSuperview];

            if (!self.webView) {

                UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Sin conexión"
                                                                message:@"No fue posible la descarga de datos debido a que no se pudo conectar con el servidor"
                                                               delegate: nil
                                                      cancelButtonTitle: @"OK"
                                                      otherButtonTitles: nil];

                [alert show];
            }
        });
    });
}

- (void)toggleNavBar:(UITapGestureRecognizer *)gesture {

    BOOL barsHidden = self.navigationController.navigationBar.hidden;
    [self.navigationController setNavigationBarHidden:!barsHidden animated:YES];

}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

@end