objective-c - Objective-C 中的 Mime 编码字解析

Question

OS X 或 iOS 是否提供 API 来解析 MIME Encoded-Word ？这些可爱的字符串:

=?iso-8859-1?Q?=A1Hola,_se=F1or!?=

或者，是否有已知的开源库可以执行此操作？

Answer 1

我拿走了@NickolayO. 的answer , 添加 base-64 支持 QSStrings并使用 componentsSeparatedByString: 和 stringByReplacingOccurrencesOfString:withString: 缩短了代码。

我已经在 GitHub 上提供了代码.为方便起见，这里有一个片段:

@implementation NSString (MimeEncodedWord)

- (BOOL) isMimeEncodedWord
{
    return [self hasPrefix:@"=?"]  && [self hasSuffix:@"?="];
}

+ (NSString*) stringWithMimeEncodedWord:(NSString*)word
{ // Example: =?iso-8859-1?Q?=A1Hola,_se=F1or!?=
    NSArray *components = [word componentsSeparatedByString:@"?"];
    if (components.count < 5) return nil;

    NSString *charset = [components objectAtIndex:1];
    NSStringEncoding encoding = CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding((CFStringRef)charset)); // TODO: What happens if the encoding is invalid?

    NSString *encodingType = [components objectAtIndex:2];
    NSString *encodedText = [components objectAtIndex:3];
    if ([encodingType isEqualToString:@"Q"])
    { // quoted-printable
        encodedText = [encodedText stringByReplacingOccurrencesOfString:@"_" withString:@" "];
        encodedText = [encodedText stringByReplacingOccurrencesOfString:@"=" withString:@"%"];
        NSString *decoded = [encodedText stringByReplacingPercentEscapesUsingEncoding:encoding];
        return decoded;
    } else if ([encodingType isEqualToString:@"B"])
    { // base64
        NSData *data = [QSStrings decodeBase64WithString:encodedText];
        NSString *decoded = [[NSString alloc] initWithData:data encoding:encoding];
        return decoded;
    } else {
        NSLog(@"%@ is not a valid encoding (must be Q or B)", encodingType);
        return nil;
    }    
}

@end