How do I get a reference to the app delegate in Swift?

Question

How do I get a reference to the app delegate in Swift?

Ultimately, I want to use the reference to access the managed object context.

Answer 1

The other solution is correct in that it will get you a reference to the application's delegate, but this will not allow you to access any methods or variables added by your subclass of UIApplication, like your managed object context. To resolve this, simply downcast to "AppDelegate" or what ever your UIApplication subclass happens to be called. In Swift 3, 4 & 5, this is done as follows:

let appDelegate = UIApplication.shared.delegate as! AppDelegate
let aVariable = appDelegate.someVariable

Answer 2

Swift 4.2

In Swift, easy to access in your VC's

extension UIViewController {
    var appDelegate: AppDelegate {
    return UIApplication.shared.delegate as! AppDelegate
   }
}

Answer 3

Convenience Constructors

Add in AppDelegate Class at the end of code

Swift 5

func appDelegate() -> AppDelegate {
    return UIApplication.shared.delegate as! AppDelegate
}

To use AppDelegate reference in your class?

---

Call AppDelegate Method

appDelegate().setRoot()

Answer 4

This could be used for OS X

let appDelegate = NSApplication.sharedApplication().delegate as AppDelegate
var managedObjectContext = appDelegate.managedObjectContext?

Answer 5

It's pretty much the same as in Objective-C

let del = UIApplication.sharedApplication().delegate

Answer 6

Here is the Swift 5 version:

let delegate = UIApplication.shared.delegate as? AppDelegate

And to access the managed object context:

    if let delegate = UIApplication.shared.delegate as? AppDelegate {

        let moc = delegate.managedObjectContext
        
        // your code here
        
    }

or, using guard:

    guard let delegate = UIApplication.shared.delegate as? AppDelegate  else {
        return
    }

    let moc = delegate.managedObjectContext
        
    // your code here
    

Answer 7

Appart from what is told here, in my case I missed import UIKit:

import UIKit

Answer 8

SWIFT < 3

Create a method in AppDelegate Class for ex

func sharedInstance() -> AppDelegate{
        return UIApplication.sharedApplication().delegate as! AppDelegate
    }

and call it some where else for ex

let appDelegate : AppDelegate = AppDelegate().sharedInstance()

SWIFT >= 3.0

func sharedInstance() -> AppDelegate{
    return UIApplication.shared.delegate as! AppDelegate
}

Answer 9

Try simply this:

Swift 4

// Call the method
(UIApplication.shared.delegate as? AppDelegate)?.whateverWillOccur()

where in your AppDelegate:

// MARK: - Whatever
func whateverWillOccur() {

    // Your code here.

}

Answer 10

1. Make sure you import UIKit

2. let appDelegate = UIApplication.sharedApplication().delegate! as! AppDelegate

Answer 11

Here's an extension for UIApplicationDelegate that avoids hardcoding the AppDelegate class name:

extension UIApplicationDelegate {

    static var shared: Self {    
        return UIApplication.shared.delegate! as! Self
    }
}

// use like this:
let appDelegate = MyAppDelegate.shared // will be of type MyAppDelegate

Answer 12

it is very simple

App delegate instance

let app = UIApplication.shared.delegate as! AppDelegate

you can call a method with one line syntax

app.callingMethod()

you can access a variable with this code

app.yourVariable = "Assigning a value"

Answer 13

In my case, I was missing import UIKit on top of my NSManagedObject subclass. After importing it, I could remove that error as UIApplication is the part of UIKit

Hope it helps others !!!

Answer 14

I use this in Swift 2.3.

1.in AppDelegate class

static let sharedInstance: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

2.Call AppDelegate with

let appDelegate = AppDelegate.sharedInstance

Answer 15

extension AppDelegate {

    // MARK: - App Delegate Ref
    class func delegate() -> AppDelegate {
        return UIApplication.shared.delegate as! AppDelegate
    }
}

Answer 16

In Swift 3.0 you can get the appdelegate reference by

let appDelegate = UIApplication.shared.delegate as! AppDelegate

Answer 17

As of iOS 12.2 and Swift 5.0, AppDelegate is not a recognized symbol. UIApplicationDelegate is. Any answers referring to AppDelegate are therefore no longer correct. The following answer is correct and avoids force-unwrapping, which some developers consider a code smell:

import UIKit

extension UIViewController {
  var appDelegate: UIApplicationDelegate {
    guard let appDelegate = UIApplication.shared.delegate else {
      fatalError("Could not determine appDelegate.")
    }
    return appDelegate
  }
}

Answer 18

In the Xcode 6.2, this also works

let appDelegate = UIApplication.sharedApplication().delegate! as AppDelegate

let aVariable = appDelegate.someVariable