Eli Miller Eli Miller - 1 year ago 74
iOS Question

ios: <Error>: CGAffineTransformInvert: singular matrix

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
MoreTabPages = [NSArray arrayWithObjects:self.aboutWebView,
self.creditsResourceWebView, nil];
titles = [[NSArray alloc] initWithObjects:@"About Locavore",
@"News and Updates",
@"Credits and Resources", nil];

//Initialize the URLs
websites = [[NSArray alloc] initWithObjects:@"http://www.getlocavore.com/",
@"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 {
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.

//Create a frame for each page and add the page to the scroll view

//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
self.MoreTabScrollView.contentSize = CGSizeMake(self.MoreTabScrollView.frame.size.width * MoreTabPages.count,
self.MoreTabScrollView.scrollsToTop = NO;
self.MoreTabScrollView.contentOffset = CGPointMake(self.MoreTabScrollView.frame.size.width, 0);
self.MoreTabPageControl.numberOfPages = MoreTabPages.count;

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];

Answer Source

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.

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