iOS lazy instantiation in swift

[grandM]

So guys

I was fooling around with Lazy Instantiation in Swift. Everything works using following code:

lazy var appDelegate: AppDelegate = (UIApplication.sharedApplication().delegate) as! AppDelegate
lazy var managedObjectContext: NSManagedObjectContext = {
        let appDelegate = (UIApplication.sharedApplication().delegate) as! AppDelegate
        return appDelegate.managedObjectContext
    }()

Both variables were defined as Stored Variable Properties. However when I try to use the lazyily instantiated Stored Variable Property in the initialization of the second Stored Variable Property (hence deleting let appDelegate = (UIApplication.sharedApplication().delegate) as! AppDelegate in the lazy var managedObjectContext closure) I'm getting an error. This error states: instance member 'appDelegate' cannot be used on type ViewController.

Can somebody explain me what I'm doing wrong? Thanks!

 

[AxoNeuron]

Do this:

lazy var appDelegate: AppDelegate = (UIApplication.sharedApplication().delegate) as! AppDelegate
var managedObjectContext: NSManagedObjectContext {
    get {
        return appDelegate.managedObjectContext;
    }
}

The appDelegate variable is already using lazy instantiation. The object context is just a property of it. The only place you would use lazy instantiation of the "managedObjectContext" would be in the AppDelegate file, which is unnecessary since Apple has already given good code for this.

 

[grandM]

Do this:

lazy var appDelegate: AppDelegate = (UIApplication.sharedApplication().delegate) as! AppDelegate
var managedObjectContext: NSManagedObjectContext {
    get {
        return appDelegate.managedObjectContext;
    }
}

The appDelegate variable is already using lazy instantiation. The object context is just a property of it. The only place you would use lazy instantiation of the "managedObjectContext" would be in the AppDelegate file, which is unnecessary since Apple has already given good code for this.

Thanks
I presume I couldn't write

 var managedObjectContext = appDelegate.managedObjectContext

because the appDelegate was lazy instantiated?