Question: I am new to openstack. I have recently done a single node openstack installation in my ubuntu virtual machine from the following tutorial:-

<http://www.openflowhub.org/display/floodlightcontroller/Install+Floodlight+and+OpenStack+on+Your+Own+Ubuntu+VM>

And i was able to access the services through Horizon. But after a restart, i was not able to access anything of openstack. So i had to re-run stack.sh during which i got the following error in the quantum net-create command :-

```
Usage: quantum [OPTIONS] <command> [args]
quantum: error: no such option: --tenant_id

```

Can anyone please help me with this?

Answer: 
The first line should theoretically work, but you're not instantiating your JACenterViewController in such a way that viewDidLoad will be called - and therefor your CustomClass instance is not loaded.

To ensure that viewDidLoad is called, instantiate your JACenterViewController with a nib.
Probably like
`JACenterViewController *viewController = [[JACenterViewController alloc] initWithNibName:nil bundle:nil];`

That way your viewDidLoad will be called and you should then get your delegate instantiated.
Singleton:
A class that always returns the same instances of itself. it provides a global access point for all the resources within the class. 

in CustomClass.h: add 

```
+(CustomClass*)sharedObject;

```

in CustomClass.m: add

```
static CustomClass *sharedSingleton = nil;

+(CustomClass*)sharedObject {
        @synchronized(self) {
        if (!sharedSingleton) {
                sharedSingleton = [[CustomClass alloc] init];
            } return sharedSingleton;
        }
}

+(id)alloc {
        @synchronized(self) {
            NSAssert(sharedSingleton == nil, @"Attempted to allocate a second instance of a singleton");
                sharedSingleton = [super alloc];
                return sharedSingleton;
            } return nil;

```

}

Any class you like to pass and receive messages include this header file in that class and initialize with the factory method .