非同期通信

NSMutableData *receivedData;

//非同期通信
- (void)startConnection{
    
    NSURL *url = [NSURL URLWithString:@"http://xxxx.jp/"];
    NSURLRequest *request=[NSURLRequest requestWithURL:url];
    NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
    
    if (!connection) {
        //エラー
    }
}


//通信開始
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    receivedData = [[NSMutableData data] retain];
}

//通信中(何度も呼ばれる)
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    // データを追加する
    [receivedData appendData:data];
}

//通信終了
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    NSString *dataStr = [[[NSString alloc] initWithData:receivedData encoding:NSUTF8StringEncoding] autorelease];
    //受信データをログに表示
    NSLog(@"%@", dataStr);
    
    [receivedData release];
    receivedData = nil;
    [connection release];
}

//通信エラー
- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    //アラートを出す
    NSString *erroMessage = [error localizedDescription];
    UIAlertView *alert = [[[UIAlertView alloc] initWithTitle:@"Error" message:erroMessage delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil] autorelease];
    [alert show];
}