Question

我正在尝试将XML解析为json格式。我使用XMLReader第三方库（从Github下载）。解析xml后，我得到NULL结果。我试图打印NSError值，错误是“NSErrorDomain code = 4而Document is Empty”。我能做什么？任何人都可以帮忙吗？

这是我的ViewDidLoad（）代码：

  NSDictionary *xmlDict =  [[NSDictionary alloc]init];

   NSError *parseError = nil;

    xmlDict = [XMLReader dictionaryForXMLString:@"abc.xml"];  // which call's the XMLReader Class Method

   NSLog(@"MAIN CLASS OF Dictionary: %@",xmlDict);  // Gives the NULL Results.

这是我的XMLReader.h代码

 #import <Foundation/Foundation.h>

  @interface XMLReader : NSObject <NSXMLParserDelegate>
      {
        NSMutableArray *dictionaryStack;
        NSMutableString *textInProgress;
         NSError *errorPointer;
        }

       + (NSDictionary *)dictionaryForXMLData:(NSData *)data error:(NSError **)errorPointer;
       + (NSDictionary *)dictionaryForXMLString:(NSString *)string error:(NSError **)errorPointer;

          @end

这是我的XMLReader.m代码

     #import "XMLReader.h"

        NSString *const kXMLReaderTextNodeKey = @"text";

           @interface XMLReader (Internal)

         - (id)initWithError:(NSError **)error;
          - (NSDictionary *)objectWithData:(NSData *)data;

            @end

           @implementation XMLReader

             #pragma mark -
             #pragma mark Public methods

            + (NSDictionary *)dictionaryForXMLData:(NSData *)data error:(NSError **)error
              {
              XMLReader *reader = [[XMLReader alloc] initWithError:error];
               NSDictionary *rootDictionary = [reader objectWithData:data];

             return rootDictionary;
                }

           + (NSDictionary *)dictionaryForXMLString:(NSString *)string error:(NSError **)error
              {
               NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
                return [XMLReader dictionaryForXMLData:data error:error];
                   }

           #pragma mark Parsing

              - (NSDictionary *)objectWithData:(NSData *)data
                    {
                    // Clear out any old data

                       dictionaryStack = [[NSMutableArray alloc] init];
                      textInProgress = [[NSMutableString alloc] init];

                        // Initialize the stack with a fresh dictionary
                         [dictionaryStack addObject:[NSMutableDictionary dictionary]];

                      // Parse the XML
                       NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data];
                        parser.delegate = self;
                         BOOL success = [parser parse];

                 // Return the stack's root dictionary on success
              if (success)
               {
                  NSDictionary *resultDict = [dictionaryStack objectAtIndex:0];
                  return resultDict;
                  }

              return nil;
            }

       #pragma mark NSXMLParserDelegate methods

        - (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
          {
         // Get the dictionary for the current level in the stack
            NSMutableDictionary *parentDict = [dictionaryStack lastObject];

           // Create the child dictionary for the new element, and initilaize it with the attributes
             NSMutableDictionary *childDict = [NSMutableDictionary dictionary];
              [childDict addEntriesFromDictionary:attributeDict];

                // If there's already an item for this key, it means we need to create an array
                 id existingValue = [parentDict objectForKey:elementName];
              if (existingValue)
              {
                  NSMutableArray *array = nil;
                 if ([existingValue isKindOfClass:[NSMutableArray class]])
                   {
                       // The array exists, so use it
                          array = (NSMutableArray *) existingValue;
                    }
                      else
                         {
                  // Create an array if it doesn't exist
                   array = [NSMutableArray array];
                   [array addObject:existingValue];

                  // Replace the child dictionary with an array of children dictionaries
                      [parentDict setObject:array forKey:elementName];
                    }

                  // Add the new child dictionary to the array
                   [array addObject:childDict];
                 }
              else
                {
                // No existing value, so update the dictionary
                    [parentDict setObject:childDict forKey:elementName];
                    }

               // Update the stack
                  [dictionaryStack addObject:childDict];
                   }

               - (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
                 {
                 // Update the parent dict with text info
                     NSMutableDictionary *dictInProgress = [dictionaryStack lastObject];

            // Set the text property
               if ([textInProgress length] > 0)
                   {
                        [dictInProgress setObject:textInProgress forKey:kXMLReaderTextNodeKey];

          // Reset the text

             textInProgress = [[NSMutableString alloc] init];
           }

                 // Pop the current dict
                    [dictionaryStack removeLastObject];
            }

           - (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
             {
                // Build the text value
                     [textInProgress appendString:string];
               }

                       - (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
                {
                       // Set the error pointer to the parser's error object
                     errorPointer = parseError;
                      NSLog(@"ERROR PONIT IS:  %@",errorPointer);
                   }

          @end

所以，在这段代码中，我用于将xml数据解析为字典格式。任何人都可以帮我解决这个问题吗？

Answer 1

尝试这样的事情。 Decalre在AppDelegate.h文件中的方法下面

+(void)downloadDataFromURL:(NSURL *)url withCompletionHandler:(void(^)(NSData *data))completionHandler;

在AppDelegate.m文件中添加方法定义

+(void)downloadDataFromURL:(NSURL *)url withCompletionHandler:(void (^)(NSData *))completionHandler{
// Instantiate a session configuration object.
      NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];

// Instantiate a session object.
      NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration];

// Create a data task object to perform the data downloading.
      NSURLSessionDataTask *task = [session dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

    if (error != nil) {
        // If any error occurs then just display its description on the console.
        NSLog(@"%@", [error localizedDescription]);
    }
    else{
        // If no error occurs, check the HTTP status code.
        NSInteger HTTPStatusCode = [(NSHTTPURLResponse *)response statusCode];

        // If it's other than 200, then show it on the console.
        if (HTTPStatusCode != 200) {
            NSLog(@"HTTP status code = %d", HTTPStatusCode);
        }

        // Call the completion handler with the returned data on the main thread.
        [[NSOperationQueue mainQueue] addOperationWithBlock:^{
            completionHandler(data);
        }];
    }
}];
}

现在从viewDtroller中调用此方法，如viewDidload

[AppDelegate downloadDataFromURL:url withCompletionHandler:^(NSData *data) {
    // Make sure that there is data.
    if (data != nil) {
        xmlDict = [XMLReader dictionaryForXMLData:data error:&parseError];
    }
}];

希望这会对你有所帮助

解析后的XMLParser在字典中给出NULL值

1 个答案: