Question

我有一个自iOS 4开始使用quartz / UIKit快乐生成PDF的应用程序，但是自从将项目升级到iOS 8后，每当它尝试将文本呈现到PDF上下文时就会崩溃。画线＆amp;矩形很好，但字符串渲染的任何排列都会失败，其中一个低级库也会出现异常。

我尝试从Apple的文档中倒退，而不是发布我自己的来源。虽然它已经过时了，但如果它不再适用，它们应该修复它。

https://developer.apple.com/library/ios/documentation/2DDrawing/Conceptual/DrawingPrintingiOS/GeneratingPDF/GeneratingPDF.html

改编的源代码：

- (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;
}

我尝试了很多排列，但它们在呈现文本的确切位置似乎都失败了。上面的Apple派生的例子终止于：

CTFrameDraw(frameRef, currentContext);

其他代码尝试获得最低工作量：

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];

...在“drawAtPoint”电话中崩溃。

Answer 1

对于它的价值，如果我在未连接调试器的设备上执行应用程序（即从跳板运行/ kill / launch），PDF创建工作正常。据推测，任何被抛出的虚假异常都会在现实生活中被忽略。

iOS 8 API打印PDF：绘制文本时是否已损坏？

1 个答案: