iAd Banner Error "Too many instances of iAd" - ios7

Question

I have an ad banner view on one my view controllers that acts as an instructional page for my game. When that view controller has been loaded multiple times I receive the following error.
WARNING: More than 10 instances of ADBannerView or ADInterstitialView currently exist. This is a misuse of the iAd API, and ad performance will suffer as a result. This message is printed only once.
I have searched this error on stackoverflow, read the responses but nothing has worked for me. I have read that you are meant to release the ad banner and then nil it etc. which I have and still am receiving this error. The code for my "viewWillAppear" and "viewWillDissapear" is below. Any help will be appreciated!
-(void) viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
_adBanner = [[ADBannerView alloc] initWithFrame:CGRectMake(0, self.view.frame.size.height, 320, 50)];
_adBanner.delegate = self;
[self.view addSubview:_adBanner];
}
-(void) viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
if (_adBanner != nil) {
_adBanner.delegate = nil;
_adBanner.hidden = YES;
[_adBanner release];
_adBanner = nil;
}
}

Answer 1

Try removing the iAd from its superview before setting it to nil:
-(void) viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
if (_adBanner != nil) {
[_adBanner removeFromSuperview]; // <-new line
_adBanner.delegate = nil;
_adBanner.hidden = YES;
[_adBanner release];
_adBanner = nil;
}

Answer 2

Here is the code for iAd that I am already using in my apps with no problems:
implementation ViewController
{
ADBannerView *adView;
BOOL bannerIsVisible;
}
- (void)viewDidLoad
{
[super viewDidLoad];
adView = [[ADBannerView alloc] initWithFrame:CGRectZero];
adView.frame = CGRectOffset(adView.frame, 0, -50);
adView.requiredContentSizeIdentifiers = [NSSet setWithObject:ADBannerContentSizeIdentifier320x50];
adView.currentContentSizeIdentifier = ADBannerContentSizeIdentifier320x50;
[self.view addSubview:adView];
adView.delegate=self;
bannerIsVisible=NO;
}
- (void)bannerViewDidLoadAd:(ADBannerView *)banner
{
if (!bannerIsVisible)
{
[UIView beginAnimations:#"animateAdBannerOn" context:NULL];
// banner is invisible now and moved out of the screen on 50 px
banner.frame = CGRectOffset(banner.frame, 0, 50);
[UIView commitAnimations];
bannerIsVisible = YES;
}
}
- (void)bannerView:(ADBannerView *)banner didFailToReceiveAdWithError:(NSError *)error
{
if (bannerIsVisible)
{
[UIView beginAnimations:#"animateAdBannerOff" context:NULL];
// banner is visible and we move it out of the screen, due to connection issue
banner.frame = CGRectOffset(banner.frame, 0, -50);
[UIView commitAnimations];
bannerIsVisible = NO;
}
}

Answer 3

Instead of initializing the adBannerView in the individual class, create it in the AppDelegate.
I put:
#property (strong, nonatomic) ADBannerView *adBanner;
in my AppDelegate.h and:
self.adBanner = [[ADBannerView alloc] init];
in my AppDelegate.m
And then in the individual class I put:
#property (strong, nonatomic) ADBannerView *adBanner;
in the .h and in the .m I put:
{
BOOL _bannerIsVisible;
}
right below the #interface and in the #implementation I put:
#pragma mark Ads
- (WTMAppDelegate *) appdelegate {
return (WTMAppDelegate *)[[UIApplication sharedApplication] delegate];
}
- (void)bannerViewDidLoadAd:(ADBannerView *)banner
{
NSLog(#"Retreieved Ad");
[self bringBannerBack];
}
- (void)bannerView:(ADBannerView *)banner didFailToReceiveAdWithError:(NSError *)error
{
NSLog(#"Failed to retrieve ad");
[self moveBannerViewOffScreen];
}
- (void)bringBannerBack
{
[self.adBanner setAlpha:1];
[self.adBanner setNeedsDisplay];
[UIView beginAnimations:#"MoveView" context:nil];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationDuration:0.1];
self.adBanner.frame = CGRectMake(0, self.view.bounds.size.height - 50, 320, 50);
[UIView commitAnimations];
_bannerIsVisible = YES;
[self.adBanner setAlpha:1];
}
//Move the banner off the screen.
- (void)moveBannerViewOffScreen
{
[self.adBanner setAlpha:0];
[self.adBanner setNeedsDisplay];
_bannerIsVisible = NO;
}
and in the viewWillAppear and ViewWillDisappear:
- (void) viewWillDisappear:(BOOL)animated{
self.adBanner.delegate=nil;
self.adBanner=nil;
[self.adBanner removeFromSuperview];
}
- (void) viewWillAppear:(BOOL)animated
{
self.adBanner = [[self appdelegate] adBanner];
self.adBanner.delegate = self;
[self.view addSubview:self.adBanner];
if (self.adBanner.bannerLoaded == NO){
NSLog(#"NO initial banner loaded");
[self moveBannerViewOffScreen];
} else {
NSLog(#"Initial ad loaded");
[self bringBannerBack];
}
}