I can't receive XML file from Weather Underground service - iphone

Question

I'm trying to write a weather app that use wunderground api...
I've got an apiKey and I used it in the code below, but I can't see any result in debug area...
Xcode show me a warning in a line "EXPRESSION RESULT UNUSED"...Is this the problem?
Can anybody help me please?
#import "WeatherForecast.h"
#import "MainViewController.h"
#implementation WeatherForecast
- (void) queryServiceWithState:(NSString *)state
andCity:(NSString *)city
withParent:(UIViewController *)controller {
viewController = (MainViewController *)controller;
responseData = [NSMutableData data];
apiKey = #"c5f79118382c6e91";
NSString *url =
[NSString stringWithFormat:
#"http://api.wunderground.com/api/%#/conditions/q/%#//%#.xml",
apiKey, state, city];
theURL = [NSURL URLWithString:url];
NSURLRequest *request = [NSURLRequest requestWithURL:theURL];
[[NSURLConnection alloc] initWithRequest:request delegate:self];//EXPRESSION RESULT UNUSED
}
#pragma mark NSURLConnection Delegate Methods
- (NSURLRequest *)connection:(NSURLConnection *)connection
willSendRequest:(NSURLRequest *)request
redirectResponse:(NSURLResponse *)response{
#autoreleasepool {
theURL = [request URL];
}
return request;
}
- (void)connection:(NSURLConnection *)connection
didReceiveResponse:(NSURLResponse *)response {
[responseData setLength:0];
}
-(void)connection:(NSURLConnection *)connection
didReceiveData:(NSData *)data {
[responseData appendData:data];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
NSLog(#"Error = %#",error);
}
- (void)connectionDidFinishiLoading: (NSURLConnection *)connection {
NSString *content =
[[NSString alloc]initWithBytes:[responseData bytes]
length:[responseData length]
encoding:NSUTF8StringEncoding];
NSLog ( #"Data = %#",content);
//...Insert code to parse the content here...
[viewController updateView];
}
#end
I've got another 2 .m files for my app, maybe the error is in one of this
#import "MainViewController.h"
#import "WeatherForecast.h"
#interface MainViewController ()
#end
#implementation MainViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self refreshView:self];
}
- (IBAction)refreshView:(id)sender {
[loadingActivityIndicator startAnimating];
[self.forecast queryServiceWithState:#"UK" andCity:#"London" withParent:self];
}
- (void)updateView {
//...
[loadingActivityIndicator stopAnimating];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark - Flipside View
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller
{
[self dismissViewControllerAnimated:YES completion:nil];
}
- (IBAction)showInfo:(id)sender
{
FlipsideViewController *controller = [[FlipsideViewController alloc]
initWithNibName:#"FlipsideViewController" bundle:nil];
controller.delegate = self;
controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentViewController:controller animated:YES completion:nil];
}
#end
And
#import "AppDelegate.h"
#import "WeatherForecast.h"
#import "MainViewController.h"
#implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:
(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
self.mainViewController = [[MainViewController alloc]
initWithNibName:#"MainViewController" bundle:nil];
WeatherForecast *forecast = [[WeatherForecast alloc] init];
self.mainViewController.forecast = forecast;
self.window.rootViewController = self.mainViewController;
[self.window makeKeyAndVisible];
return YES;
}
- (void)applicationWillResignActive:(UIApplication *)application
{
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
}
- (void)applicationWillTerminate:(UIApplication *)application
{
}
#end
If I try to turn off internet connection I can see in the debug area the "Error message", but if I turn on internet connection, so I only see the Activity Indicator spinning forever...
Thank you for your response....I feel lost...

Answer 1

Where you get EXPRESSION RESULT UNUSED is the connection object. You should usually be storing that into a property so you ensure that it isn't destroyed while you're still using it.