NSRegularExpression:enumerateMatchesInString在多次调用时挂起

Question

在我正在开发的iPhone应用程序的上下文中,我正在使用NSRegularExpression解析一些html来提取要映射的数据.只要用户将地图"平移"到新位置,就会更新此信息.

这在第一次或第二次通过时工作正常,但在第二次或第三次调用该函数时,应用程序挂起.我已经使用XCode的分析器来确认我没有泄漏内存,并且没有生成错误(应用程序没有终止,它只是在下面显示的位置执行).

当我检查正在解析的HTML时,我不会看到它在应用程序挂起时不完整或出现乱码.

此外,如果我用显式地址字符串的集合替换正则表达式代码,一切都按预期工作.

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
   // receivedData contains the returned HTML
   NSString *result = [[NSString alloc] initWithData:receivedData encoding:NSASCIIStringEncoding];
   NSError *error = nil;
   NSString *pattern = @"description.*?h4>(.*?)<\\/h4>.*?\"address>[ \\s]*(.*?)<.*?zip>.*?(\\d{5,5}), US<";
   NSRegularExpression *regex = [NSRegularExpression         
                              regularExpressionWithPattern:pattern
                              options:NSRegularExpressionDotMatchesLineSeparators
                              error:&error];
   __block NSUInteger counter = 0;
   // the application hangs on the next line after 1-2 times through
   [regex enumerateMatchesInString:result options:0 range:NSMakeRange(0, [result length]) usingBlock:^(NSTextCheckingResult *match, NSMatchingFlags flags, BOOL *stop){
       NSRange range = [match rangeAtIndex:2];
       NSString *streetAddress =[result substringWithRange:range];
       range = [match rangeAtIndex:3];
       NSString *cityStateZip = [result substringWithRange:range];
       NSString *address = [NSString stringWithFormat:@"%@ %@", streetAddress, cityStateZip];
       EKItemInfo *party = [self addItem:address]; // geocode address and then map it
      if (++counter > 4) *stop = true;        
   }];
   [receivedData release];
   [result release];
   [connection release]; //alloc'd previously, so release here.
}

我意识到这将很难/不可能复制,但我想知道是否有人遇到类似NSRegularExpression的问题或者这里有什么明显的错误.

Answer 1

我也遇到了正则表达式异常.就我而言,问题是字符编码.所以我写了一个代码,以便与几个字符编码相配.也许这段代码可以帮到你.

+ (NSString *)encodedStringWithContentsOfURL:(NSURL *)url
{
    // Get the web page HTML
    NSData *data = [NSData dataWithContentsOfURL:url];

    // response
    int enc_arr[] = {
        NSUTF8StringEncoding,           // UTF-8
        NSShiftJISStringEncoding,       // Shift_JIS
        NSJapaneseEUCStringEncoding,    // EUC-JP
        NSISO2022JPStringEncoding,      // JIS
        NSUnicodeStringEncoding,        // Unicode
        NSASCIIStringEncoding           // ASCII
    };
    NSString *data_str = nil;
    int max = sizeof(enc_arr) / sizeof(enc_arr[0]);
    for (int i=0; i<max; i++) {
        data_str = [
                    [NSString alloc]
                    initWithData : data
                    encoding : enc_arr[i]
                    ];
        if (data_str!=nil) {
            break;
        }
    }
    return data_str;    
}

您可以从GitHub下载整个类别库并运行它.我希望这对你有所帮助.

https://github.com/weed/p120801_CharacterEncodingLibrary