问iOS 8应用编程接口打印PDF:绘制文本时损坏？

EN

- (void)producePDF
{
    NSString *text=@"Bzorg blarf gloop foo!";
    CFAttributedStringRef currentText = CFAttributedStringCreate(NULL, (CFStringRef)text, NULL);

    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(currentText);

    NSString *pdfFileName = fullPath;
    // Create the PDF context using the default page size of 612 x 792.
    UIGraphicsBeginPDFContextToFile(pdfFileName, CGRectZero, nil);

    CFRange currentRange = CFRangeMake(0, 0);
    NSInteger currentPage = 0;
    BOOL done = NO;

    do {
        // Mark the beginning of a new page.
        UIGraphicsBeginPDFPageWithInfo(CGRectMake(0, 0, 612, 792), nil);

        // Draw a page number at the bottom of each page.
        currentPage++;
        //[self drawPageNumber:currentPage];

        // Render the current page and update the current range to
        // point to the beginning of the next page.
        //currentRange = [self renderPageWithTextRange:currentRange andFramesetter:framesetter];
        currentRange=[self renderPage:currentPage withTextRange:currentRange andFramesetter:framesetter];

        // If we're at the end of the text, exit the loop.
        if (currentRange.location == CFAttributedStringGetLength((CFAttributedStringRef)currentText))
            done = YES;
    } while (!done);

    // Close the PDF context and write the contents out.
    UIGraphicsEndPDFContext();

    // Release the framewetter.
    CFRelease(framesetter);

    // Release the attributed string.
    CFRelease(currentText);
}

- (CFRange)renderPage:(NSInteger)pageNum withTextRange:(CFRange)currentRange
                 andFramesetter:(CTFramesetterRef)framesetter
{
   // Get the graphics context.
   CGContextRef    currentContext = UIGraphicsGetCurrentContext();

   // Put the text matrix into a known state. This ensures
   // that no old scaling factors are left in place.
   CGContextSetTextMatrix(currentContext, CGAffineTransformIdentity);

   // Create a path object to enclose the text. Use 72 point
   // margins all around the text.
   CGRect    frameRect = CGRectMake(72, 72, 468, 648);
   CGMutablePathRef framePath = CGPathCreateMutable();
   CGPathAddRect(framePath, NULL, frameRect);

   // Get the frame that will do the rendering.
   // The currentRange variable specifies only the starting point. The framesetter
   // lays out as much text as will fit into the frame.
   CTFrameRef frameRef = CTFramesetterCreateFrame(framesetter, currentRange, framePath, NULL);
   CGPathRelease(framePath);

   // Core Text draws from the bottom-left corner up, so flip
   // the current transform prior to drawing.
   CGContextTranslateCTM(currentContext, 0, 792);
   CGContextScaleCTM(currentContext, 1.0, -1.0);

   // Draw the frame.
   CTFrameDraw(frameRef, currentContext);

   // Update the current range based on what was drawn.
   currentRange = CTFrameGetVisibleStringRange(frameRef);
   currentRange.location += currentRange.length;
   currentRange.length = 0;
   CFRelease(frameRef);

   return currentRange;
}

CTFrameDraw(frameRef, currentContext);

NSMutableParagraphStyle* textStyle = NSMutableParagraphStyle.defaultParagraphStyle.mutableCopy;
textStyle.alignment = NSTextAlignmentLeft;
NSDictionary* textFontAttributes = @{
    NSFontAttributeName: [UIFont fontWithName: @"Helvetica" size: 12], NSForegroundColorAttributeName: UIColor.redColor,
    NSParagraphStyleAttributeName: textStyle};
[@"Hello, World!" drawAtPoint:CGPointZero withAttributes:textFontAttributes];