解析後的XMLParser在字典中給出NULL值

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我正試圖將XML解析爲json格式。我使用XMLReader第三方庫（從Github下載）。解析XML後，我得到NULL結果。我試圖打印出錯的NSError值是「NSErrorDomain code = 4，Document is Empty」。我能做什麼？任何人都可以幫助嗎？解析後的XMLParser在字典中給出NULL值

這裏是我的viewDidLoad（）代碼：

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.

這是我XMLReader.h代碼

#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

這是我的XMLReader。 m代碼

 #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，在這段代碼中我使用XML數據解析字典格式。任何人都可以幫助我解決這個問題嗎？

來源

2016-06-13 sarosar

你得到錯誤，因爲你需要傳遞XML字符串而不是你的ur湖 –

感謝Replay Nirav。你能解釋如何在這段代碼中使用XML網址嗎？ – sarosar

嘗試類似這樣的東西。 Decalre低於AppDelegate.h方法文件

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

添加在AppDelegate.m方法定義文件

+(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); 
     }]; 
    } 
}]; 
}

現在從您的viewController這樣viewDidLoad方法中調用此方法

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

希望這會幫助你

來源

2016-06-13 11:40:24

你試過我的答案嗎？ –

是的。它運作良好。謝謝Nirav。 – sarosar

解析後的XMLParser在字典中給出NULL值

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