Snapshot of View Doesn't Render - ios

Question

I'm trying to get a snapshot of another controller's view to use in an animation. I'm using the following code, but I see nothing but the background color of that view, and none of its subviews (two buttons, a text view, and a label):
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
FirstPageController *fpController = [self.storyboard instantiateViewControllerWithIdentifier:#"FirstPage"];
UIGraphicsBeginImageContext(fpController.view.bounds.size);
NSLog(#"%#",fpController.view.subviews);
[fpController.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGSize destinationSize = CGSizeMake(90, 122);
UIGraphicsBeginImageContext(destinationSize);
[viewImage drawInRect:CGRectMake(0,0,destinationSize.width,destinationSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self.imageView2 = [[UIImageView alloc] initWithImage:newImage];
self.imageView2.center = self.view.center;
[self.view addSubview:self.imageView2];
NSLog(#"%#",NSStringFromCGSize(self.imageView2.image.size));
}
I've logged all the relevant things, the fpController, the imageView, the image, and all are logging correctly.
After Edit: If I switch to the current controller's view, it works fine, so I'm thinking that this has to do with getting a snapshot of a view that's not on screen. Can that be done?

Answer 1

Hope this will help you:
CGSize textcontent =CGSizeMake(width, height);
UIGraphicsBeginImageContext(textcontent);
if ([UIScreen instancesRespondToSelector:#selector(scale)] && [[UIScreen mainScreen] scale] == 2.0f)
{
UIGraphicsBeginImageContextWithOptions(textcontent, YES, 1.0f);
}
else
{
UIGraphicsBeginImageContext(textcontent);
}
[image.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return viewImage;

Answer 2

UIGraphicsBeginImageContextWithOptions(fpController.view.bounds.size, NO, 0.0);
UIGraphicsBeginImageContextWithOptions(destinationSize, NO, 0.0);
Use this two lines instead of UIGraphicsBeginImageContext(fpController.view.bounds.size);
UIGraphicsBeginImageContext(destinationSize); respectively
hope it help's you

Answer 3

I found one way to make this work, though it seems like a hack. I add the view I want to render as a subview of my view, do the rendering, and then remove the view. It is never seen on screen, so visually, it's fine. I just wonder whether there's a better way.
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
self.fpController = [self.storyboard instantiateViewControllerWithIdentifier:#"FirstPage"];
[self.view insertSubview:self.fpController.view belowSubview:self.view];
UIGraphicsBeginImageContext(self.fpController.view.bounds.size);
[self.fpController.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self.fpController.view removeFromSuperview];
self.imageView2 = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 90, 122)];
self.imageView2.image = viewImage;
[self.pageView insertSubview:self.imageView2 belowSubview:self.imageView];
}