Threaded programming in Objective-C, for sending request to a web server

I'm in this kind of situation... I want to patch 100 different web requests, but it's separated in three different functions:

-(void)functionMain {
    for(int i = 0; i < 100; i++)
        [self sendRequestToServer];
}

So that first function will basically send request to some URL and wait for it to finish...

-(void)sendRequestToServer {
    [request sendRequest:mAddress];
    [request didFinishSelector:@"refreshAddress"];
    [request startAsynchronous];
}

This function above will do the actual sending of the address.

-(void)refreshAddress {
    NSString *result = [requ开发者_JAVA百科est getResponse];
    mAddress = [result getTheNextAddress];
    [self refreshDisplay];
}

Now this will set mAddress to the next web address. So I got a lot of this, and apparently one request takes a bit of time (around 600 ms), but if you notice in the main loop in functionMain, I don't have any mechanism to see whether refreshAddress has finished doing its job, because it it hasn't then I'll only be sending request with the same address over and over.

I tried using a boolean variable to guard the loop, but it doesn't look like it's working... Is there any graceful way to do this? I'm not sure what should I look for.. I don't know if NSOperation or NSThread will help me.

EDIT: As I mentioned in the comment, this is probably more like I'm having a multi-threading situation here (to be exact this might be 100 threads) that I want to make into only a single thread.

EDIT: So what I really want is like this (suppose the loop is only 3):

functionMain(i = 0) -> 
sendRequestToServer

Then we wait until that finishes, then we have this:

refreshAddress (mAddress has been set to something else now) -> 
functionMain (i = 1) -> 
sendRequestToServer

Once again:

refreshAddress (mAddress has been set to something else now) -> 
functionMain (i = 2, finished)

Very very sorry if I can't describe the problem more clearly... I wish I can write better english and can describe things clearer!

Possibly I'm not following you here but if you want them to happen one after the other you should use a synchronous request in NSURLConnection.

+ sendSynchronousRequest:returningResponse:error: