ios: <Error>: CGAffineTransformInvert: singular matrix - ios

Question

Any reason for this error "CGAffineTransformInvert"
Should I be worried?
I have a .xib with a view, and 4 webViews located outside of the view but within the same xib. Then in the code I add the webViews as subviews to a scroll view inside the view. Would that cause the problem?
Code is below:
//Called first to initialize this class. Also, initializes the nib file and tab bar name.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
self.title = NSLocalizedString(#"More", #"More");
self.tabBarItem.image = [UIImage imageNamed:#"first"];
}
return self;
}
//Initialize the more tab titles and views
-(void)initViewsandTitles{
MoreTabPages = [NSArray arrayWithObjects:self.aboutWebView,
self.newsUpdateWebView,
self.feedbackWebView,
self.creditsResourceWebView, nil];
titles = [[NSArray alloc] initWithObjects:#"About Locavore",
#"News and Updates",
#"Feedback",
#"Credits and Resources", nil];
}
//Initialize the URLs
-(void)initURLs{
websites = [[NSArray alloc] initWithObjects:#"http://www.getlocavore.com/",
#"http://twitter.com/enjoy_locavore",
#"https://getsatisfaction.com/localdirt/products/localdirt_locavore",
#"http://www.getlocavore.com/about", nil];
}
//Called after the controller's view is loaded into memory.
- (void)viewDidLoad
{
[super viewDidLoad]; //Call the super class init method
[self setupSpinner]; //Start the spinner animatio
[self initViewsandTitles]; //Initialize the views and titles
[self initURLs]; //Initialize the URLs
[self setScrollandPageViewProperties]; //Set the scroll and page view properties
[self setUpPageViews]; //Create the web pages
}
//UIScrollViewDelegate Protocol Reference. Called whn the user scrolls the content within the reciever
- (void)scrollViewDidScroll:(UIScrollView *)sender {
if (!pageControlBeingUsed) {
// Switch the indicator when more than 50% of the previous/next page is visible
CGFloat pageWidth = self.MoreTabScrollView.frame.size.width;
int page = floor((self.MoreTabScrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
self.MoreTabPageControl.currentPage = page;
self.MoreTabTitle.text = [titles objectAtIndex:page];
}
}
//UIScrollViewDelegate Protocol Reference. Called when the scroll view is about to start scolling content
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
pageControlBeingUsed = NO;
}
//UIScrollViewDelegate Protocol Reference. Called when the scroll view has ended decelerating the scrolling movement
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
NSLog(#"DID END SCROLLING");
pageControlBeingUsed = NO;
}
//Called when the page control value changes
- (IBAction)MoreTabChangePage {
// Update the scroll view to the appropriate page
CGRect frame;
frame.origin.x = self.MoreTabScrollView.frame.size.width * self.MoreTabPageControl.currentPage;
frame.origin.y = 0;
frame.size = self.MoreTabScrollView.frame.size;
[self.MoreTabScrollView scrollRectToVisible:frame animated:YES];
self.MoreTabTitle.text = [titles objectAtIndex:self.MoreTabPageControl.currentPage];
// Keep track of when scrolls happen in response to the page control
// value changing. If we don't do this, a noticeable "flashing" occurs
// as the the scroll delegate will temporarily switch back the page
// number.
pageControlBeingUsed=YES;
}
//Create a frame for each page and add the page to the scroll view
-(void)setUpPageViews{
//Set up all page views for the more tab
for (int i = 0; i < MoreTabPages.count; i++) {
//Get the current table view controller page
UIWebView *webController= [MoreTabPages objectAtIndex:i];
//Request the URL and load the request
NSURL *urll =[NSURL URLWithString:[websites objectAtIndex:i]];
//Run requests in seperate thread
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0);
dispatch_async(queue, ^{
NSURLRequest *firstReq = [NSURLRequest requestWithURL:urll];
[webController loadRequest:firstReq];
dispatch_sync(dispatch_get_main_queue(), ^{
//Create a frame for the current table view controller
CGRect frame = webController.frame;
frame.origin.x = self.MoreTabScrollView.frame.size.width * i;
frame.origin.y = 0;
frame.size = self.MoreTabScrollView.frame.size;
webController.frame = frame;
//Add the the current table view controller page to the scroll view
[self.MoreTabScrollView addSubview:webController];
//Release the controller object it is no longer needed
[webController release];
if(i == 3){
[spinner stopAnimating];
}
});
});
}
}
//Set al the properties for the scroll view and page controll
-(void)setScrollandPageViewProperties{
self.MoreTabScrollView.contentSize = CGSizeMake(self.MoreTabScrollView.frame.size.width * MoreTabPages.count,
self.MoreTabScrollView.frame.size.height);
self.MoreTabScrollView.scrollsToTop = NO;
self.MoreTabScrollView.contentOffset = CGPointMake(self.MoreTabScrollView.frame.size.width, 0);
self.MoreTabPageControl.numberOfPages = MoreTabPages.count;
}
-(void)setupSpinner{
spinner.hidesWhenStopped = YES;
[spinner startAnimating];
}
//Called if the application receives a memory warning
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
//Called when the UIViewController's reference count goes to zero
- (void)dealloc {
[super dealloc];
[MoreTabPageControl release];
[MoreTabScrollView release];
[MoreTabTitle release];
[MoreTabPages release];
[titles release];
[websites release];
[spinner release];
}
#end

Answer 1

try setting the minimum zoom scale for your each webview.
[self.aboutWebView.scrollView setMinimumZoomScale:0.1]
it will throw the same error if the scrollview reaches zero at zero zoom.

Answer 2

This may happen with affine transformations when you're scaling UIScrollView instance to 0 either using setZoomScale:animated: method or zoomScale property, so please check your scroll views.
Make sure your zoomScale, minimumZoomScale and maximumZoomScale to set to at least 0.1.
Related:
Calculating minimumZoomScale of a UIScrollView
UIScrollView not respecting minimumZoomScale after changing the subview