Question

大家好我正在研究Objective-C。我以前的问题是How can I edit PDF files in an iOS application? 经过大量的谷歌搜索，我发现了以下内容。在UIWebView中显示pdf，使用C / javascript提取数据并进行编辑。我仍然不确定这个程序。现在我的计划是

1）显示pdf

2）当用户想要编辑pdf时我将pdf转换为文本并允许他编辑它

3）试着保存将内容转换回pdf。

这是一种继续进行的方式吗？即时通讯步骤1.现在我如何转换pdf - ＆gt;文字和文字 - ＆gt; pdf。

提前致谢

Answer 1

当您将自定义文档类型（doc，ppt，pdf等）加载到UIWebView中时，webview会返回一个nil HTML字符串，即使是通过javascript也是如此。有一些提取PDF文本的建议here。

但将字符串转换回PDF是不同的。如果你想保留原始PDF的格式，我相信这是不可能的，因为iOS上的NSAttributedString并没有做太多。但是这可以用于纯文本或NSAttributedString，如果可能的话：

NSData *PDFDataFromString(NSString *str) {
    NSMutableData *data = [NSMutableData data];

    //Create an NSAttributedString for CoreText. If you find a way to translate
    //PDF into an NSAttributedString, you can skip this step and simply use an
    //NSAttributedString for this method's argument.

    NSAttributedString* string = [[[NSAttributedString alloc] initWithString:str] autorelease];

    //612 and 792 are the dimensions of the paper in pixels. (8.5" x 11")
    CGRect paperRect = CGRectMake(0.0, 0.0, 612, 792);

    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef) string);
    CGSize requiredSize = CTFramesetterSuggestFrameSizeWithConstraints(framesetter, CFRangeMake(0, [string length]), NULL, CGSizeMake(paperRect.size.width - 144, 1e40), NULL);

    //Subtract the top and bottom margins (72 and 72), so they aren't factored in page count calculations.
    NSUInteger pageCount = ceill(requiredSize.height / (paperRect.size.height - 144));
    CFIndex resumePageIndex = 0;
    UIGraphicsBeginPDFContextToData(data, paperRect, nil);

    for(NSUInteger i = 0; i < pageCount; i++) 
    {

    //After calculating the required number of pages, break up the string and
    //draw them into sequential pages.

        UIGraphicsBeginPDFPage();
        CGContextRef currentContext = UIGraphicsGetCurrentContext();
        CGContextSaveGState (currentContext);
        CGContextSetTextMatrix(currentContext, CGAffineTransformIdentity);
        CGMutablePathRef framePath = CGPathCreateMutable();

        //72 and 72 are the X and Y margins of the page in pixels.
        CGPathAddRect(framePath, NULL, CGRectInset(paperRect, 72.0, 72.0));

        CTFrameRef frameRef = CTFramesetterCreateFrame(framesetter, CFRangeMake(resumePageIndex, 0), framePath, NULL);
        resumePageIndex += CTFrameGetVisibleStringRange(frameRef).length;
        CGPathRelease(framePath);
        CGContextTranslateCTM(currentContext, 0, paperRect.size.height);
        CGContextScaleCTM(currentContext, 1.0, -1.0);
        CTFrameDraw(frameRef, currentContext);
        CFRelease(frameRef);    
        CGContextRestoreGState (currentContext);
    }
    CFRelease(framesetter);
    UIGraphicsEndPDFContext();
    return data;
}

将pdf文件转换为文本文件

1 个答案: