Objective-C将XML解析为NSManagedObjects

我正在做的是:解析XML以创建NSManagedObject子类,但总是解析失败。

此处代码:

NSData* data = [[NSString stringWithUTF8String:answerString.c_str()] dataUsingEncoding:NSUTF8StringEncoding];

NSXMLParser *nsXmlParser = [[NSXMLParser alloc] initWithData:data];

XMLParser *parser = [[XMLParser alloc] initXMLParser];

[nsXmlParser setDelegate:parser];

BOOL success = [nsXmlParser parse];

哪里 answerString 是 std::string 。我总是 NO 在里面 success 旗帜

我的对象类:

@interface System : NSManagedObject

@property (nonatomic, retain) NSString * systemFullName;
@property (nonatomic, retain) NSString * systemShortName;

@end

我的解析器标头:

@class System;

@interface XMLParser : NSObject <NSXMLParserDelegate>
{
    NSMutableString *currentElementValue;

    System *system;
}

- (XMLParser *) initXMLParser;

和实施:

- (XMLParser *) initXMLParser
{
    self = [super init];
    return self;
}

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName 
namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName 
attributes:(NSDictionary *)attributeDict
{
    if ([elementName isEqualToString:@"System"])
{
    system = [NSEntityDescription insertNewObjectForEntityForName:@"System" 
    inManagedObjectContext:((AppDelegate*)[[UIApplication sharedApplication] 
    delegate]).managedObjectContext];
}
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    if (!currentElementValue)
    {
        currentElementValue = [[NSMutableString alloc] initWithString:string];
    } else
    {
        [currentElementValue appendString:string];
    }
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName 
namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    NSManagedObjectContext *context = ((AppDelegate*)[[UIApplication sharedApplication] 
 delegate]).managedObjectContext;

if ([elementName isEqualToString:@"System"])
{
    [context save:nil];
    system = nil;
}

if ([elementName isEqualToString:@"systemFullName"])
{
    system.systemFullName = currentElementValue;
}

if ([elementName isEqualToString:@"systemShortName"])
{
    system.systemShortName = currentElementValue;
}
}

有什么想法吗?

我跌跌撞撞,什么时候方法 didEndElement 找到第一个对象的结尾,XMLParser就停止工作,出现错误111。