1. 官方方法

1.1 HTML String => NSAttributedString

- (nullable NSAttributedString *)getAttributedStringFromHTMLString:(NSString *)string
{
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
    NSDictionary *options = @{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,
                              NSCharacterEncodingDocumentAttribute: @(NSUTF8StringEncoding)};
    
    if (data)
    {
        return [[NSAttributedString alloc] initWithData:data options:options documentAttributes:nil error:nil];
    }
    
    return nil;
}

PS: 这个方法会丢失 HTML String 中删除线的样式

1.2 NSAttributedString => HTML String

- (nullable NSString *)getHTMLStringFromAttributedString:(NSAttributedString *)attributedString
{
    NSDictionary *documentAttributes = @{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType};
    NSData *data = [attributedString dataFromRange:NSMakeRange(0, attributedString.length) documentAttributes:documentAttributes error:NULL];
    
    if (data)
    {
        return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    }
        
    return nil;
}

2. DTCoreText

为了解决删除线信息在转换过程中丢失的问题，我们改用了 DTCoreText。

2.1 HTML String => NSAttributedString

2.2 NSAttributedString => HTML String