IOS: Receive a “Received Memory Warning” after using an image created from PDF and used as background

Question

Task: create an image from a PDF file as a quick preview for my PDF file displayed with CATiledLayer(slower, higher resolution). Problem: I get a rather quick error warning on my iPad, “Memory Alert: Level = 1” and shortly after “Received Memory Alert. Level = 2” .. then the application crashes.

- (void) drawSinglePage:(CALayer *)layer inContext:(CGContextRef)ctx {
    CGContextSaveGState(ctx);
    CGContextSetRGBFillColor(ctx, 1.0, 1.0, 1.0, 1.0);
    CGContextFillRect(ctx, CGContextGetClipBoundingBox(ctx));
    @synchronized(self) {

        // Draw PDF for HighRes
        CGPDFPageRef page = CGPDFDocumentGetPage(page1, 1);
        CGRect pageRect = CGPDFPageGetBoxRect(page, kCGPDFCropBox);
        CGFloat scaleRatio = 960/pageRect.size.height;
        CGFloat yOffset = ((960-pageRect.size.height)/scaleRatio)+960;

        CGContextTranslateCTM(ctx, -(layer.bounds.size.width-pageRect.size.width)/2, yOffset);
        CGContextScaleCTM(ctx, scaleRatio, -scaleRatio);
        CGContextConcatCTM(ctx, CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, layer.bounds, 0, true));
        CGContextDrawPDFPage(ctx, page);

        // Draw Background-Image as fast preview (PROBLEM HERE!!)
        UIGraphicsBeginImageContext(layer.bounds.size);
        CGContextRef context = UIGraphicsGetCurrentContext();

        CGContextSetRGBFillColor(context, 1.0, 1.0, 1.0, 1.0);
        CGRect prob = CGContextGetClipBoundingBox(context);
        CGContextFillRect(context, prob);

        CGContextSaveGState(context);
        CGContextSetInterpolationQuality(context, kCGInterpolationLow);
        CGContextTranslateCTM(context, -(layer.bounds.size.width-pageRect.size.width)/2, yOffset);
        CGContextScaleCTM(context, scaleRatio, -scaleRatio);
        CGContextConcatCTM(context, CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, CGRectMake(0.0, 0.0, layer.bounds.size.width, layer.bounds.size.height), 0, true));
        CGContextDrawPDFPage(context, page);
        CGContextRestoreGState(context);
        UIImage *back = UIGraphicsGetImageFromCurrentImageContext();
        NSData *jpegDataFile = UIImageJPEGRepresentation(back, 0.2f);
        UIImage *smBack = [[UIImage alloc] initWithData:jpegDataFile];      
        UIGraphicsEndImageContext();

        // Now set the subview
        UIImageView *backgroundImageView = [[UIImageView alloc] initWithImage:smBack];
        backgroundImageView.frame = CGRectMake(0.0, 0.0, smBack.size.width, smBack.size.height);
        backgroundImageView.contentMode = UIViewContentModeTopLeft;
        backgroundImageView.opaque = YES;
        [self.view addSubview:backgroundImageView];
        [self.view sendSubviewToBack:backgroundImageView];
        [backgroundImageView release];

    }
    CGContextRestoreGState(ctx);
}

}

: , - , - , . . : "CGPDFDocumentRelease(page1)" - (void)dealloc ViewController.

Answer 1

, drawSinglePage:inContext: , , . , , .

, , ( imageView.image = nil), . , .

, pdf 20 . , , , . .

Answer 2

https://github.com/mindbrix/UIImage-PDF (BSD?), PDF UIImage.

, , CGPDFDocument . , CGPDFDocument , iPad UIImageJPEGRepresentation . , (CGPDFPage, CGPDFDocument) .

, CGPDFDocument , . , . ( PDF .)