Using NSURLConnection to retrieve data - ios

Question

I've got this api (http://www.timeapi.org/utc/now) that just gives the time as a string and I want to use NSURLConnection to retrieve it, except I'm confused as to how NSURLConnection works.
Current code:
+(NSString *) fetchTime
{
NSString *timeString=#"not_set";
//Code for URL request here
NSURL *timeURL = [NSURL URLWithString:#"http://www.timeapi.org/utc/now"]
return timeString;
}
The method is called from the view controller that will then in turn display it on the screen as per MVC, all I need is a good example to get me in the right direction.

Answer 1

In order to make a request to that api you need something like this:
NSURL *timeURL = [NSURL URLWithString:#"http://www.timeapi.org/utc/now"]
NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url
cachePolicy:NSURLRequestReloadIgnoringCacheData
timeoutInterval:120];
NSData *urlData;
NSURLResponse *response;
NSError *error;
urlData = [NSURLConnection sendSynchronousRequest:urlRequest
returningResponse:&response
error:&error];
NSString *string = [[NSString alloc] initWithData:urlData encoding:NSUTF8StringEncoding];

Answer 2

What you want to do is send an Asynchronous request to the server to fetch the Time. If you send out a synchronous request it will block your UI and for some reason if server took a minute to send the response back user wont be able to do anything for a minute. Example using the standard API :
Note that if you are using sync request you can expect a return value but in async calls you would need the help of a block to return the value. So
-(void) fetchTimeFromServerWithCompletionHandler:(void(^)(id)) onComplete {
NSURLRequest *timeRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://www.timeapi.org/utc/now"]];
[NSURLConnection sendAsynchronousRequest:timeRequest queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *urlResponse, NSData *data, NSError *error) {
// Do something usefull with Data.
// If expected object is a String, alloc init a String with received Data
NSString *time = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
onComplete(time); // This will return back the time string.
}];
}
If you are using service API a lot in your app, you can check out AFNetworking as well.
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:#"http://example.com/resources.json" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#"JSON: %#", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Error: %#", error);
}];