iOS 8.1中CGContextDrawPDFPage中的内存泄漏？

Question

Under iOS 8.1 I'm getting a memory leak when rendering a PDF page into a graphics context with CGContextDrawPDFPage. It doesn't happen in the simulator but I get hundreds of leaks of 272 bytes of malloc'd memory every time I do it (on iPad Air). If I comment out the CGContextDrawPDFPage the leak goes away.

Does anyone else get similar behaviour?

CGDataProviderRef dataProvider = CGDataProviderCreateWithCFData((CFDataRef)data);
CGPDFDocumentRef pdf = CGPDFDocumentCreateWithProvider(dataProvider);


CGPDFPageRef page;

// Grab the PDF page
page = CGPDFDocumentGetPage(pdf, pageNo + 1);

UIGraphicsBeginImageContext(aRect.size);
CGContextRef context = UIGraphicsGetCurrentContext();

CGContextTranslateCTM(context, 0, aRect.size.height);
CGContextScaleCTM(context, 1, -1);

CGContextDrawPDFPage(context, page); // <-  LEAKING?!?!?

// Would create the new UIImage from the context
//image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

CGPDFDocumentRelease(pdf);
CGDataProviderRelease(dataProvider);

Here's a stack trace (reversed):

malloc

38.58 MB 36.7% 148743 std::__1::list >::list(std::__1::list > const&)

19.61 MB 18.6% 75610 std::__1::vector CG::Path::Subpath CG::Allocator

19.61 MB 18.6% 75610 void std::__1::vector >::__push_back_slow_path(CG::Path::Subpath&&)

19.61 MB 18.6% 75610 CG::Path::Sequence::move_to_point(CGPoint const&, CGAffineTransform const*)

19.61 MB 18.6% 75610 CGPathMoveToPoint

19.59 MB 18.6% 75506 TTrueTypeQuadOutlineContext::AddPoint(bool, int, int)

19.59 MB 18.6% 75506 TTrueTypeFontHandler::RenderGlyph(unsigned short, TTrueTypeQuadOutlineContext&, unsigned int) const

19.59 MB 18.6% 75506 TTrueTypeFontHandler::GetOutlinePath(unsigned short, TGlyphOutlineBatch const&) const

19.59 MB 18.6% 75506 FPFontCopyGlyphPath

19.59 MB 18.6% 75506 CGFontCreateGlyphPath

19.59 MB 18.6% 75506 CGFontCreateGlyphBitmap

19.59 MB 18.6% 75506 CGGlyphBuilder::create_missing_bitmaps(CGGlyphIdentifier const*, unsigned long, CGGlyphBitmap const**)

19.59 MB 18.6% 75506 render_glyphs

19.59 MB 18.6% 75506 draw_glyph_bitmaps

19.59 MB 18.6% 75506 ripc_DrawGlyphs

19.59 MB 18.6% 75506 draw_glyphs

19.57 MB 18.6% 75434 draw_glyphs

19.55 MB 18.6% 75359 simple_draw

19.55 MB 18.6% 75359 CGPDFTextLayoutDrawGlyphs

19.55 MB 18.6% 75348 op_TJ

19.55 MB 18.6% 75348 pdf_scanner_handle_xname

19.55 MB 18.6% 75348 CGPDFScannerScan

19.55 MB 18.6% 75348 CGPDFDrawingContextDrawPage

19.55 MB 18.6% 75348 pdf_page_draw_in_context

19.55 MB 18.6% 75348 CGContextDrawPDFPage

Answer 1

Yes, you need to call UIGraphicsEndImageContext() to match every call to UIGraphicsBeginImageContext() .

Per the UIKit framework reference :

When you are done modifying the context, you must call the UIGraphicsEndImageContext function to clean up the bitmap drawing environment and remove the graphics context from the top of the context stack. You should not use the UIGraphicsPopContext function to remove this type of context from the stack.