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下面的代码来自 iOS 开发中心：http: //developer.apple.com/library/ios/#documentation/2ddrawing/conceptual/drawingprintingios/GeneratingPDF/GeneratingPDF.html

问题是，事情似乎一团糟。例如，它在声明此类参数之前引用“Context”和“currentRange”。任何人都可以从中得出正面或反面吗？也许我应该在其他地方声明那些，比如在“UIGraphicsBeginPDFPage”函数中？我知道您的 .m 文件中需要有“#import”。

- (CFRange)renderPage:(NSInteger)pageNum withTextRange:(CFRange)currentRangeandFramesetter:(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(Context, 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;
}

- (void)drawPageNumber:(NSInteger)pageNum
{
NSString* pageString = [NSString stringWithFormat:@"Page %d", pageNum];
UIFont* theFont = [UIFont systemFontOfSize:12];
CGSize maxSize = CGSizeMake(612, 72);

CGSize pageStringSize = [pageString sizeWithFont:theFont
                               constrainedToSize:maxSize
                                   lineBreakMode:UILineBreakModeClip];
CGRect stringRect = CGRectMake(((612.0 - pageStringSize.width) / 2.0),
                               720.0 + ((72.0 - pageStringSize.height) / 2.0) ,
                               pageStringSize.width,
                               pageStringSize.height);

[pageString drawInRect:stringRect withFont:theFont];
}
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1 回答 1

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currentRange是方法的参数。看起来你在那里失去了一个空间：currentRangeandFramesetter应该是currentRange andFramesetter

Context是一个错字，应该是currentContext。除此之外，代码编译。

于 2012-06-11T12:11:53.230 回答