UITextview 加载html，怎么才能全部充满，使内容自适应

是这样的：服务器返回字符串经过 Unicode转码后生成HTMLString，然后用UITextview加载，怎么才能让充满整个textview，
NSString *htemlString =[LBService stringFromUnicode:detailModel.contentStr];

    NSAttributedString *attributedSting =[[NSAttributedString alloc]initWithData:[htemlString dataUsingEncoding:NSUnicodeStringEncoding] options:@{NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType} documentAttributes:nil error:nil];
    self.textView.attributedText = attributedSting;
   
CGFloat height = [LBService stringSizeWithFont:[UIFont systemFontOfSize:12] string:htemlString width:300].height ;
    
    self.textView.frame = CGRectMake(0, 64, 300, height
                                     );
    self.textView.contentSize =CGSizeMake(300, height);