renderInContext占用大量内存，最终崩溃

Question

My UIView is very large and I'm trying to convert it into a pdf. I am using renderInContext for generating image of a UIView . After executing renderInContext the memory goes up by 100 MB only for 1/6th of the view.

If the whole view is rendered, then the memory goes to around 350 MB or so in simulator but it'll crash in device. I have tried rendering view part by part, but the memory keeps increasing.

The allocated memory isn't being released immediately after creating the image. I have tried changing imageNamed to imageWithContentsOfFile but no luck.

Is there any way I can achieve this?

I have referred to many answers but no luck.

Any help would be appreciated...

Here is the code for generating image:

UIGraphicsBeginImageContextWithOptions(aView.bounds.size, NO, 0.0);
CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0, 0);
[aView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

Then I use this image to convert to pdf file. But while executing renderInContext I'm getting a memory spike. It then never lowers.

Answer 1

I've been using renderInContext recently and while it's very taxing on the CPU I saw no effect at all on memory usage. Are you able to use the alternative: drawViewHierarchyInRect: afterScreenUpdates: It's much faster for me so I guess it may also be more efficient and help with your memory issue.

That method renders to the context and then you can just call:

CGImageRef image = CGBitmapContextCreateImage(UIGraphicsGetCurrentContext());

Answer 2

This answer might help someone so I'm answering it.

For large drawing, I had to use drawViewHierarchyInRect: afterScreenUpdates: but it should be executed inside an autoreleasepool . If not the memory keeps on rising.

For smaller drawing renderInContext is better.