Get data from asynchronous requests in right order - iphone

Question

I need to load data from my API without waiting 20s each time I launch my application.
So I use:
NSURL *myUrlCourses = [[NSURL alloc] initWithString:url];
NSMutableURLRequest *request = [NSURLRequest requestWithURL: myUrlCourses];
NSURLConnection *connexion = [[NSURLConnection alloc] initWithRequest:request delegate:self];
for my 10 first request in while loop which permit to get data in background.
But, when I get data from this request with:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{}
The result don't match.
So, I think I have to use thread or something like that to get the right data for each request but I don't really know how!?
Could you help me to solve this problem?
Thanks

Answer 1

Store all of your connections in variables with describing names and then compare the pointer values.
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
if(connection == _theFacebookConnection)
{
//Handle Facebook code
}
else if(connection == _theTwitterConnection)
{
//Handle Twitter code
}
}

Answer 2

I use a CFMutableDictionaryRef to save another mutable dictionary for each connection. This inner dictionary can hold as much data as you want.
like this:
#interface Foo {
CFMutableDictionaryRef connections;
}
#implementation Foo
- (id)init {
self = [super init];
if (self) {
connections = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
}
return self;
}
- (BOOL)addURLRequest:(NSURLRequest *)request successSelector:(SEL)successSelector errorSelector:(SEL)errorSelector {
NSMutableDictionary *connectionInfo = [NSMutableDictionary dictionaryWithObjectsAndKeys:
[NSMutableData data], #"receivedData",
[NSValue valueWithPointer:successSelector], #"successSelector",
[NSValue valueWithPointer:errorSelector], #"errorSelector",
request, #"request",
nil];
NSURLConnection *connection = [[[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:NO] autorelease];
CFDictionaryAddValue(connections, connection, connectionInfo);
[connection start];
return YES;
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
NSMutableDictionary *connectionInfo = (NSMutableDictionary *)CFDictionaryGetValue(connections, connection);
[[connectionInfo objectForKey:#"receivedData"] appendData:data];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSMutableDictionary *connectionInfo = (NSMutableDictionary *)CFDictionaryGetValue(connections, connection);
NSData *data = [connectionInfo objectForKey:#"receivedData"];
LogInfo(#"Finished Connection %#", connection);
SEL selector = [[connectionInfo objectForKey:#"successSelector"] pointerValue];
if ([self respondsToSelector:selector]) {
[self performSelector:selector withObject:data];
}
CFDictionaryRemoveValue(connections, connection);
}

Answer 3

I use ASIHTTPRequest for this sort of thing because I can use [request setUserInfo:(NSDictionary *)] to specify additional data that travels around with the request responses.
Then when I receive each response, I can look at that requests UserInfo dictionary and process the data accordingly.
What's nice about this is you can put as much or as little data into the UserInfo Dictionary as you require.