How can I pause the program until nsurlconnection complete? - objective-c

Question

I know that people have asked this but I have not found satisfactory answers. I have one method that I send all my URLRequests through. I return the response of the request as a string when the method completes. I have recently added ssl to my program. This means that I can no longer use a synchronous request because I need to take advantage of the didReceiveAuthenticationChallenge function as my credentials are currently self-signing. The program needs the response from the URL in order to continue so there is not harm in waiting for the response. However, I cannot seem to find a way to just hold the code up and continue once completed. I can alert the original function that called to request function but I would like the program to pick up right after that call. And it has unique code below such calls so I cannot specialize the connectionDidFinishLoading: function because each method who calls this is different.
How can I pause the program so I can return the nsdata from the connection to the methods that called it?
Here is some pseudo-code to show you what I mean:
- (void) login:(NSString *)username :(NSString *)password {
NSString *str = [NSString stringWithFormat:%#"%#:::%#",username,password];
NSURL *url = [NSURL urlWithString:#"https://blahblahblah"];
NSString *result = [self connectToUrl:str:url];
if ([result isEqualToString:#"valid"]) {
//this would be more complex in here
NSLog(#"hooray");
} else {
NSLog(#"bummer");
}
}
- (NSString *)connectToUrl:(NSURL *)url :(NSString *)str {
NSData *FileData = [str dataUsingEncoding: NSUTF8StringEncoding];
NSMutableData *data = [[NSMutableData alloc] initWithCapacity:100];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
[request setHTTPMethod:#"POST"];
//set up the rest of the request...
...
connection = [NSURLConnection connectionWithRequest:request delegate:self];
[connection start];
//WOULD LIKE TO PAUSE HERE UNTIL COMPLETE! THEN CONTINUE
// received data is assigned in didReceiveData: method
return [[[NSString alloc] initWithData:receivedData encoding:NSUTF8StringEncoding] autorelease];
}
But alas, I cannot do this because I cannot make the final line wait until the connection is complete... Please help me!
Very appreciative!
R

Answer 1

iOS and OS X and much of the Cocoa/Cocoa touch frameworks are built on an event model. You don't pause your app. That's not the proper approach. You need to start the connection and then move on. When the connection completes, you act on that event.
In other words, your login method can't sit and wait for the result. It should start the connection and return.
When you get the result of the connection you call some method to process the login result.
Making use of blocks can make things like this easier but there are other ways. You just need to stop thinking about such things in a linear fashion. Dealing with asynchronous processing requires a different approach.