for (int i = 0; i < 20; i++) {
    [Weather loadWeatherInformationWithCallBack:^(NSArray *array, NSError *error) {
        if (error) {
            NSLog(@"%@", error);
            return;
        } else {
            self.testArray = [self.testArray arrayByAddingObjectsFromArray:array];
            self.weather = self.testArray;
            NSLog(@"-------------------------%d", i);
        }
    } keepFirst:NO];
 }