coretext 获取高度

- (CGFloat)richTextViewHeightWithSize:(CGSize)size{    if (_text) {        CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)self.textAttributedStr);        CGSize sz = CTFramesetterSuggestFrameSizeWithConstraints(framesetter,CFRangeMake(0,0),NULL,size,NULL);        if (framesetter) CFRelease(framesetter);        return CGSizeMake( floorf(sz.width) , floorf(sz.height)).height;// 精确高度    }    else {        return 0;    }}