How do I get a reference to the AppDelegate in Swift? - swift

Question

How do I get a reference to AppDelegate 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 5.7
func appDelegate() -> AppDelegate {
return UIApplication.shared.delegate as! AppDelegate
}
To use AppDelegate reference anywhere in code?
For example: Call AppDelegate Method named setRoot
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

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 11

Make sure you import UIKit
let appDelegate = UIApplication.sharedApplication().delegate! as! AppDelegate

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

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

Answer 14

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 15

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 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