标准的数据获取 －ios

#define kBgQueue dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)

#define kLatestKivaLoansURL [NSURL URLWithString:@"http://api.kivaws.org/v1/loans/search.json?status=fundraising"]

dispatch_async(kBgQueue, ^{

        NSData* data = [NSDatadataWithContentsOfURL:

                        kLatestKivaLoansURL];

        [selfperformSelectorOnMainThread:@selector(fetchedData:)

                               withObject:data waitUntilDone:YES]; });

- (void)fetchedData:(NSData *)responseData {

    //parse out the json data

    NSError* error;

    NSDictionary* json = [NSJSONSerialization

                          JSONObjectWithData:responseData //1

                          options:kNilOptions error:&error];

    NSArray* latestLoans = [json objectForKey:@"loans"]; //2

    NSLog(@"loans: %@", latestLoans); //3

}