EXC_BAD访问CFAttributedStringReplaceString（currentText，CFRangeMake（0,0），string）;

Question

我生成了pdf this tutorial。我需要从两个不同的视图控制器生成pdf。当我从一个视图控制器推进到我生成pdf的VC时，它不会崩溃。但是当我从第二视图控制器推进到我生成pdf的VC时，它给了我EXC_BAD Access

以下是我的代码。

- (void)drawText:(NSString*)textToDraw inFrame:(CGRect)frameRect fontSize:
(float)sizeofFont
{

    NSUInteger length = [textToDraw length];
    CFStringRef string = (__bridge CFStringRef) textToDraw;

    CFMutableAttributedStringRef currentText =
    CFAttributedStringCreateMutable(kCFAllocatorDefault, 0);

    CFAttributedStringReplaceString (currentText,CFRangeMake(0, 0), string); **//EXC_BAD_ACCESS**
    // CFAttributedStringReplaceString (currentText,CFRangeMake(0, length-1), string);

    CTFontRef font = CTFontCreateWithName((CFStringRef)@"UniversLTStd-BoldCn",
                                          sizeofFont, nil);
    CFAttributedStringSetAttribute(currentText,CFRangeMake(0,
                                                           length),kCTFontAttributeName,font);

    if (self.flagToSetBlueColoredText == NO)
    {
        CFAttributedStringSetAttribute(currentText,CFRangeMake(0, length),kCTForegroundColorAttributeName,[UIColor blackColor].CGColor);
    }
    else if(self.flagToSetBlueColoredText == YES)
    {
        CFAttributedStringSetAttribute(currentText,CFRangeMake(0, length),kCTForegroundColorAttributeName,[UIColor blueColor].CGColor);
    }

    CTFramesetterRef framesetter =
    CTFramesetterCreateWithAttributedString(currentText);

    CGMutablePathRef framePath = CGPathCreateMutable();
    CGPathAddRect(framePath, NULL, frameRect);
    CFRange currentRange = CFRangeMake(0, 0);
    CTFrameRef frameRef = CTFramesetterCreateFrame(framesetter, currentRange,
                                                   framePath, NULL);
    CGPathRelease(framePath);
    CGContextRef    currentContext = UIGraphicsGetCurrentContext();
    CGContextSetTextMatrix(currentContext, CGAffineTransformIdentity);
    CGContextTranslateCTM(currentContext, 0, frameRect.origin.y*2);
    CGContextScaleCTM(currentContext, 1.0, -1.0);
    CTFrameDraw(frameRef, currentContext);
    CGContextScaleCTM(currentContext, 1.0, -1.0);
    CGContextTranslateCTM(currentContext, 0, (-1)*frameRect.origin.y*2);
    CFRelease(frameRef);
    //CFRelease(currentText);
    CFRelease(framesetter);
    //CFRelease(stringRef);
}

Answer 1

我不知道这是不是一个好习惯，但以下代码对我有用。我处理了字符串条件并使用NULL进行了检查，并跳过了以下语句。

- (void)drawText:(NSString*)textToDraw inFrame:(CGRect)frameRect fontSize:
(float)sizeofFont
{

    NSInteger length = [textToDraw length];
    CFStringRef string = (__bridge CFStringRef) textToDraw;

    CFMutableAttributedStringRef currentText =
    CFAttributedStringCreateMutable(kCFAllocatorDefault, 0);

    if (string == NULL)
    {
        //CFAttributedStringReplaceString(nil ,range, nil);
    }
    else
    {
        CFAttributedStringReplaceString(currentText,CFRangeMake(0, 0), string); //EXC_BAD_ACCESS due to nil values of string and currentText
    }

    CTFontRef font = CTFontCreateWithName((CFStringRef)@"UniversLTStd-BoldCn",
                                          sizeofFont, nil);
    CFAttributedStringSetAttribute(currentText,CFRangeMake(0,
                                                           length),kCTFontAttributeName,font);

    if (self.flagToSetBlueColoredText == NO)
    {
        CFAttributedStringSetAttribute(currentText,CFRangeMake(0, length),kCTForegroundColorAttributeName,[UIColor blackColor].CGColor);
    }
    else if(self.flagToSetBlueColoredText == YES)
    {
        CFAttributedStringSetAttribute(currentText,CFRangeMake(0, length),kCTForegroundColorAttributeName,[UIColor blueColor].CGColor);
    }

    CTFramesetterRef framesetter =
    CTFramesetterCreateWithAttributedString(currentText);

    CGMutablePathRef framePath = CGPathCreateMutable();
    CGPathAddRect(framePath, NULL, frameRect);
    CFRange currentRange = CFRangeMake(0, 0);
    CTFrameRef frameRef = CTFramesetterCreateFrame(framesetter, currentRange,
                                                   framePath, NULL);
    CGPathRelease(framePath);
    CGContextRef    currentContext = UIGraphicsGetCurrentContext();
    CGContextSetTextMatrix(currentContext, CGAffineTransformIdentity);
    CGContextTranslateCTM(currentContext, 0, frameRect.origin.y*2);
    CGContextScaleCTM(currentContext, 1.0, -1.0);
    CTFrameDraw(frameRef, currentContext);
    CGContextScaleCTM(currentContext, 1.0, -1.0);
    CGContextTranslateCTM(currentContext, 0, (-1)*frameRect.origin.y*2);
    CFRelease(frameRef);
    //CFRelease(currentText);
    CFRelease(framesetter);
    //CFRelease(stringRef);
}