NSAttributedString设置折行方式NSLineBreakByTruncatingTail，计算高度出错，高度返回异常。

iOS13上，NSAttributedString设置折行方式NSLineBreakByTruncatingTail，计算高度出错，只返回一行的高度。

NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc]init];

style.hyphenationFactor = 1;  // 设置每行的最后单词是否截断，在0.0-1.0之间，默认为0.0，越接近1.0单词被截断的可能性越大， 

设置hyphenationFactor=1,在计算就返回正常高度了。

如果设置不起效。换下面的方法

找到了解决方案。只需将 NSMutableParagraphStyle 上的 setAllowsDefaultTighteningForTruncation 设置为 YES。

参考 cocoa - Making NSTextField not shrink when NSLineBreakByTruncatingTail is set - Stack Overflow

    NSString *highlightTitle = title;//转换参数NSDictionary *options = @{ NSDocumentTypeDocumentAttribute : NSHTMLTextDocumentType, NSCharacterEncodingDocumentAttribute :@(NSUTF8StringEncoding) };//将html文本转换为正常格式的文本NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithData:[highlightTitle dataUsingEncoding:NSUnicodeStringEncoding] options:options documentAttributes:nil error:nil];[attributedString removeAttribute:NSParagraphStyleAttributeName range: NSMakeRange(0, attributedString.length)];[attributedString addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, attributedString.length)];NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];//    paragraphStyle.hyphenationFactor = 1;[paragraphStyle setLineSpacing:space];paragraphStyle.lineBreakMode = NSLineBreakByTruncatingTail;[paragraphStyle setAllowsDefaultTighteningForTruncation:YES];[attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [attributedString length])];return attributedString;