我有下面的代码（下面给出），其中我使用NSURLConnection连接和解析响应字符串。但我得到了以下错误：

dyld: Symbol not found: _CFXMLNodeGetInfoPtr
  Referenced from: /System/Library/Frameworks/Security.framework/Versions/A/Security
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
 in /System/Library/Frameworks/Security.framework/Versions/A/Security

我已经在这方面工作了很长一段时间，但无法修复这个错误。
我已经导入了json.h和ASIHTTPRequest.h，所有这些文件，但它还没有修复错误。

@implementation Websample1ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];
    dataWebService = [[NSMutableData data] retain];
    NSMutableURLRequest *request = [[NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://www.googleapis.com/customsearch/v1?key=AIzaSyDzl0Ozijg2C47iYfKgBWWkAbZE_wCJ-2U&cx=017576662512468239146:omuauf_lfve&q=lectures&callback=handleResponse"]]retain];    

    NSURLConnection *myConnection = [NSURLConnection connectionWithRequest:request delegate:self];
    [myConnection start];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response 
{
    [dataWebService setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [dataWebService appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection 
{
    NSString *responseString = [[NSString alloc] initWithData:dataWebService encoding:NSUTF8StringEncoding];
    NSLog(@"Response: %@",responseString);
    [responseString release];
    [dataWebService release];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    NSLog(@"Error during connection: %@", [error description]);
}

//class 2
@implementation WebJson
//parse JSON
- (void)requestCompleted:(ASIHTTPRequest *)request
{
    NSString *responseString = [request responseString];   
    NSDictionary *dictionary = [responseString JSONValue];
    NSDictionary *dictionaryReturn = (NSDictionary*) [dictionary objectForKey:@"request"];    
    NSString *total = (NSString*) [dictionaryReturn objectForKey:@"totalResults"];
    NSLog(@"totalResults: %@", total); 

    NSString *search = (NSString*) [dictionaryReturn objectForKey:@"searchTerms"];
    NSLog(@"searchTerms: %@", search);       

    int count = [[dictionaryReturn objectForKey:@"count"] intValue];
    NSLog(@"count: %d", count);
}