how to wait for ui delegate in swift - ios

Question

I want to create simple object helper to sending sms in many places on my Swift 2.0 app, and in next step another helpers (email, pdf opener etc)
I create simple class:
import Foundation
import MessageUI
class SmsHelper: MFMessageComposeViewControllerDelegate {
func sendSMS(body: String){
if (MFMessageComposeViewController.canSendText()){
let messageVC = MFMessageComposeViewController()
messageVC.body = body
//messageVC.recipients = ["Enter tel-nr"]
messageVC.messageComposeDelegate = self;
AppDelegate().sharedInstance().getTopController().presentViewController(messageVC, animated: false, completion: nil)
}
else{
//do some alert etc.
}
}
func messageComposeViewController(controller: MFMessageComposeViewController, didFinishWithResult result: MessageComposeResult){
sendSMSRsp(result, errorMsg: nil)
controller.dismissViewControllerAnimated(true, completion: nil)
print("sms didFinishWithResult")
}
}
in anywhere in code I want to do that:
class someAnotherClass{
func someFunction(){
let smsHelper = SmsHelper()
smsHelper.sendSms("some text")
}
}
so sms ios editor is opened, but when I want to close it or sending, it don't dismiss, function messageComposeViewController(controller: MFMessageComposeViewController, didFinishWithResult result: MessageComposeResult) i never called and app crashes with memory leak, I know reason: is because SmsHelper object in 'someFunction' is deleting after end scope of this function, and this object is nil, and system try to call didFinishWithResult at nil object. I confirm it: when I add smsHelper object as member of 'SomeClass' it worked - delegate is called.
Question is: What is the best practice to do that, adding a member is not an option for me, because many classes can use that, also creating a singleton, appDelegate member is I think quite stupid. How to force not deleting a object at end of scope function?

Answer 1

Try to use singleton way to do it:
class SmsHelper: MFMessageComposeViewControllerDelegate {
static let sharedInstance = SmsHelper()
private init() {}
}
And usage:
SmsHelper.sharedInstance().sendSms('some text')
EDIT:
If you add different init method from abstract class.
private override init(message: String){
super.init()
}
then change definition to static let sharedInstance = SmsHelper(message:"smsHelper") won't complicated.
For your delegate, just assign it out of the init method, in the UIViewController viewDidLoad,
SmsHelper.sharedInstance().delegate = self

Answer 2

For me, the way to do this is to create a type alis of a closure, then storing an optional variable of this type alias. When you call sendSMS, you pass in a closure and set it to your variable. Then that can be called in the delegate, which will then pass it through the closure of sendSMS:
import Foundation
import MessageUI
class SmsHelper: MFMessageComposeViewControllerDelegate {
let messageVC: MFMessageComposeViewController!
typealias SMSCompletion = (result: MessageComposeResult, errorMsg: NSError?) -> ()
var sendSMSRsp: SMSCompletion?
func sendSMS(body: String, completion: SMSCompletion){
sendSMSRsp = completion
if (MFMessageComposeViewController.canSendText()){
messageVC = MFMessageComposeViewController()
messageVC.body = body
//messageVC.recipients = ["Enter tel-nr"]
messageVC.messageComposeDelegate = self;
AppDelegate().sharedInstance().getTopController().presentViewController(messageVC, animated: false, completion: nil)
} else {
//do some alert etc.
}
}
func messageComposeViewController(controller: MFMessageComposeViewController, didFinishWithResult result: MessageComposeResult){
sendSMSRsp?(result: result, errorMsg: nil)
controller.dismissViewControllerAnimated(true, completion: nil)
print("sms didFinishWithResult")
}
}
class SomeOtherClass {
func someFunction() {
let smsHelper = SmsHelper()
smsHelper.sendSMS("some text") { (result, errorMsg) -> () in
}
}
}