Ios 生成pdf文件时如何更改编码？

我正试图：

-(void)drawText:(NSString*)textToDraw inFrame:(CGRect)frameRect
{
    CFStringRef stringRef = (__bridge CFStringRef)textToDraw;   

    // Prepare the text using a Core Text Framesetter    
    CFAttributedStringRef currentText = CFAttributedStringCreate(NULL, stringRef, NULL);
    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(currentText);

    CGMutablePathRef framePath = CGPathCreateMutable();
    CGPathAddRect(framePath, NULL, frameRect);

    // Get the frame that will do the rendering.
    CFRange currentRange = CFRangeMake(0, 0);
    CTFrameRef frameRef = CTFramesetterCreateFrame(framesetter, currentRange, framePath, NULL);
    CGPathRelease(framePath);

    // Get the graphics context.
    CGContextRef currentContext = UIGraphicsGetCurrentContext();

    CGContextSetRGBFillColor(currentContext, 0.0, 0.0, 0.0, 1.0);

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

    // Core Text draws from the bottom-left corner up, so flip
    // the current transform prior to drawing.
    CGContextTranslateCTM(currentContext, 0, frameRect.origin.y*2);
    CGContextScaleCTM(currentContext, 1.0, -1.0);

    // Draw the frame.
    CTFrameDraw(frameRef, currentContext);
    CGContextScaleCTM(currentContext, 1.0, -1.0);
    CGContextTranslateCTM(currentContext, 0, (-1)*frameRect.origin.y*2);

    CFRelease(frameRef);
    CFRelease(stringRef);
    CFRelease(framesetter);

}

结果：操作系统Windows没有显示俄文字符，Mac上的所有字符都显示得非常完美

如果您从pdf文件复制文本并将其粘贴到记事本中，则会显示该文本。 请帮帮我

我找到了解决方案：haru pdf lib。