MFMessageComposeViewControllerDelegate not being called - ios

Question

I am trying to implement a class that will present a MFMessageComposeViewController from the AppDelegate. The class declaration looks like this:
import UIKit
import MessageUI
class MyClass: NSObject, MFMessageComposeViewControllerDelegate {
func sendAMessage() {
// message view controller
let messageVC = MFMessageComposeViewController()
messageVC.body = "Oh hai!"
messageVC.recipients = ["8675309"]
// set the delegate
messageVC.messageComposeDelegate = self
// present the message view controller
UIApplication.sharedApplication().keyWindow?.rootViewController?.presentViewController(messageVC, animated: true, completion: nil)
}
// delegate implementation
func messageComposeViewController(controller: MFMessageComposeViewController!, didFinishWithResult result: MessageComposeResult) {
switch result.value {
case MessageComposeResultCancelled.value:
controller.presentingViewController?.dismissViewControllerAnimated(true, completion: nil)
case MessageComposeResultFailed.value:
controller.presentingViewController?.dismissViewControllerAnimated(true, completion: nil)
case MessageComposeResultSent.value:
controller.presentingViewController?.dismissViewControllerAnimated(true, completion: nil)
default:
break
}
}
}
In my AppDelegate I am creating and calling an instance of MyClass after receiving a push notification like this:
func application(application: UIApplication, didReceiveRemoteNotification userInfo: [NSObject : AnyObject], fetchCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void) {
// instance of class
let handler = MyClass()
// call method
handler.sendAMessage()
}
Everything works fine at first--the message view controller appears and is responsive with no errors, but whenever the send or cancel button is pressed, the message view controller does not dismiss, the screen becomes unresponsive, the delegate is not called, and I get a BAD_ACCESS error.
If I put the MFMessageComposeViewControllerDelegate in the AppDelegate and set the messageVC. messageVC.messageComposeDelegate = UIApplication.sharedApplication().delegate as! MFMessageComposeViewControllerDelegate, then everything works fine and the controller dismisses as expected.
Why is the MFMessageComposeViewControllerDelegate not called when it lives in the MyClass object? Thanks for reading and helping!

Answer 1

It's crashing because your handler object is getting released and deallocated right after the call to handler.sendMessage(), and then a delegate callback is attempted on that now-deallocated object when you try to send or hit cancel. The object is getting released and deallocated because nothing is holding a strong reference to it anymore at the end of application:didReceiveRemoteNotification:.
Since you are creating this object in your app delegate, I would suggest making a property in your app delegate to hold onto this object:
var handler: MyClass?
func application(application: UIApplication, didReceiveRemoteNotification userInfo: [NSObject : AnyObject], fetchCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void) {
// instance of class
handler = MyClass()
// call method
handler?.sendAMessage()
}