ios – 使用CoreText绘制时未显示NSTextAttachment图像

出于某种原因,当使用核心文本时,我无法获得要绘制的NSTextAttachment图像,尽管当NSAttributedString添加到UILabel时,相同的图像会显示正常.

在iOS上,此渲染将为NSTextAttachments提供空白空间,对于OS X,将为每个NSTextAttachment呈现占位符[OBjeCT]方形图像.为了使用COreText渲染图像,还需要做些什么吗？

渲染代码：

CGFloat contextHeight = CGBitmapContextGetHeight(context);
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef)_attributedString);
CGPathRef path = CGPathCreateWithRect(CGRectMake(rect.origin.x,contextHeight - rect.origin.y - rect.size.height,rect.size.width,rect.size.height),null);
CTFrameRef frame = CTFramesetterCreateFrame(framesetter,CFRangeMake(0,0),path,null);
CFRelease(framesetter);
CGPathRelease(path);
CGContextSaveGState(context);
CGContextSetTextMatrix(context,CGAffineTransformIdentity);
CGContextTranslateCTM(context,0.0f,contextHeight);
CGContextScaleCTM(context,1.0f,-1.0f);
CTFrameDraw(frame,context);
CGContextRestoreGState(context);
CFRelease(framE);