Multiple NSURLConnection in a row - ios

Question

Basically I got 2 NSURLConnections.
The first gets a token from my API and the second gets some events from the API but needs the token to do that. I'm currently learning objective C/Ios stuff so this is not a real app.
What I'm trying to do is to distinguish between the two connections by my class property current_connection.
1) My first question is: Is there a better way to do this?
2) Second question: Is it safe to make 2 connections like this? Because these have to happen in this order, I don't know if IOS will always do that if my code is like this. For example if the first requests takes very long does it already start the second? That would be a problem without having a token.
3) I read about https://github.com/AFNetworking/AFNetworking - should I use it?
My Code:
HomeViewController.h
#import <UIKit/UIKit.h>
#interface HomeViewController : UIViewController
#property (nonatomic, strong) NSString* current_connection;
#end
My HomeViewController.m
#import "HomeViewController.h"
#interface HomeViewController ()
#end
#implementation HomeViewController
#synthesize current_connection;
- (void)viewDidLoad {
[super viewDidLoad];
//get user token
NSString *post = [NSString stringWithFormat:#"&email=%#&password=%#",[[NSUserDefaults standardUserDefaults] objectForKey:#"email"], [[NSUserDefaults standardUserDefaults] objectForKey:#"password"]];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:#"%lu",(unsigned long)[postData length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:[NSURL URLWithString:[NSString stringWithFormat:#"http://localhost:3000/api/v1/sessions"]]];
[request setHTTPMethod:#"POST"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Current-Type"];
[request setHTTPBody:postData];
current_connection = #"token";
NSURLConnection *conn = [[NSURLConnection alloc]initWithRequest:request delegate:self];
//load events
NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
NSString *url =[NSString stringWithFormat:#"http://localhost:3000/api/v1/events/start_events?user_email=%#&user_token=%#",[[NSUserDefaults standardUserDefaults] objectForKey:#"email"], [[NSUserDefaults standardUserDefaults] objectForKey:#"token"]];
NSMutableURLRequest *req = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];
[req setHTTPMethod:#"GET"];
current_connection = #"event";
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:req delegate:self];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData*)data {
NSError *error;
NSMutableDictionary *cdata = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers|NSJSONReadingMutableLeaves error:&error];
if( error )
{
NSLog(#"%#", [error localizedDescription]);
}
else {
if ([current_connection isEqual: #"token"]) {
NSString *token = cdata[#"token"];
NSLog(#"%#", token);
//save token to user defaults
NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:token forKey:#"token"];
[defaults synchronize];
}
else {
//display events
NSLog(#"%#", cdata[#"events"]);
}
}
}
#end

Answer 1

In response to your questions:
Yes, there are better ways to do this. There are a number of issues:
Your two connection requests will be calling the same delegate object, and they'll step over each other unless you are very careful.
In your case, since the second connection needs the first to finish (i.e. you need the token, presumably, before you start the next connection), you could fix this by putting the initiation of the second connection not immediately after the first was initiated, but where the first finishes (i.e. where you get the token).
Right now, your two requests are effectively running concurrently (you have no formal assurance as to which will finish first). You want to change this so that they run consecutively.
You are processing the responses in didReceiveData. That is dangerous because sometimes the body of a response will require more than one call to didReceiveData. Usually you (a) instantiate some NSMutableData object before initiating the request; (b) didReceiveData just appends the received data to that NSMutableData; and (c) only in connectionDidFinishLoading would you try to now use the whole NSMutableData, and process that for the web service's response.
Bottom line, this delegate based implementation has a number of problems, and I'd suggest using sendAsynchronousRequest (a nice block-based implementation that gets you out of these weeds) or AFNetworking (a nice wrapping of the delegate-based implementation in NSOperation objects). You could fix this delegate-based implementation, but it might be easier to use one of the aforementioned.
No, it is not prudent to use the same delegate object to issue two concurrent requests. Now, it turns out that you probably don't want them to be concurrent, anyway, but as a general design principle, life is easier if you have different delegate object for each NSURLConnection request.
Yes, AFNetworking is probably worth trying out. It's not perfect, but it gets you out of the weeds of the NSURLConnectionDataDelegate programming. If you don't need the full richness of AFNetworking, you could also issue requests as simple as these with NSURLConnection class method sendAsynchronousRequest.

Answer 2

its better to use + (void)sendAsynchronousRequest:(NSURLRequest*) request
queue:(NSOperationQueue*) queue
completionHandler:(void (^)(NSURLResponse* response, NSData* data, NSError* connectionError)) handler NS_AVAILABLE(10_7, 5_0); instead of using delegates.
You can create as much connection as you want there is no problem.
AFNetworking is a wonderful library that will help you to do so many things like will check for network availability and downloading stuffs asynchronously. Depending on your usage you can decide. If your app have so many network activities and need to handle different error condition better to go for AFNetwork.