NSThread is failing to load Selector method - objective-c

Question

So, I am trying to connect to a remote server to get and show data. in viewDidLoad I use an NSThread to call a function called doSomething
- (void)doSomething
{
#autoreleasepool
{
NSMutableURLRequest *httpRequest = [NSMutableURLRequest requestWithURL:someURL];
[httpRequest setHTTPMethod:#"POST"];
[httpRequest setValue:[NSString stringWithFormat:#"%d", httpRequestParametersClean.length] forHTTPHeaderField:#"Content-Length"];
[httpRequest setValue:#"application/x-www-form-urlencoded charset=utf-8" forHTTPHeaderField:#"Content-Type"];
[httpRequest setHTTPBody:httpRequestParametersClean];
(void)[[NSURLConnection alloc] initWithRequest:httpRequest delegate:self];
for (NSString* key in response)
{
// loop through returned values
}
}
}
The code in viewDidLoad is
[NSThread detachNewThreadSelector:#selector(someURL) toTarget:self withObject:nil];
Then I have a REFRESH button which when clicked calls doSomething as well
by simply saying [self doSomething]
My problem is that when view is loaded, the response from server comes empty. I still get no response until I click on the refresh button. Strange! What am I doing wrong?

Answer 1

A NSURLConnection created with initWithRequest:delegate: works asynchronously, calling the delegate functions connection:didReceiveResponse:, connection:didReceiveData:, ... later, when data is read from the server. Your code does not even start the connection, so nothing will happen anyway.
The easiest way to fix your problem is to use the synchronous version
sendSynchronousRequest:returningResponse:error:
of NSURLConnection. If doSomething is executed in a separate thread, this will not block the UI.
Added: (Thanks to #geowar for mentioning this.) Note that you can also use the delegate-based NSURLConnection methods. These are more flexible (see e.g. https://stackoverflow.com/a/15591636/1187415 for a comparison). Another good choice is sendAsynchronousRequest:queue:completionHandler:, which creates a background thread automatically.