iOS app crash when opened from today extension

Question

Possible duplicate of Crash when open containing app from today extension .

I'm trying to open the containing app from a today extension widget using a custom URL scheme. The code i'm using inside the extension is:

let urlStr = String(format: "myapp://?device_id=%@", deviceId!)
let url = NSURL(string: urlStr)
self.extensionContext!.openURL(url!, completionHandler: nil)

However, the containing app crashes when opened:

Thread : Crashed: com.apple.main-thread
0  CoreFoundation                 0x0000000103e572dc CFStringCreateCopy + 28
1  libswiftFoundation.dylib       0x0000000105f02a44 _TF10Foundation24_convertNSStringToStringFCSo8NSStringSS + 148
2  MyApp                          0x00000001017a9055 @objc MyApp.CLAppDelegate.application (MyApp.CLAppDelegate)(ObjectiveC.UIApplication, openURL : ObjectiveC.NSURL, sourceApplication : Swift.String, annotation : Swift.Optional<Swift.AnyObject>) -> Swift.Bool (CLAppDelegate.swift)
3  UIKit                          0x0000000104898685 -[UIApplication _applicationOpenURL:payload:] + 185
4  UIKit                          0x00000001048a0816 -[UIApplication _handleNonLaunchSpecificActions:forScene:withTransitionContext:] + 2380
5  UIKit                          0x00000001048a42e8 __88-[UIApplication _handleApplicationLifecycleEventWithScene:transitionContext:completion:]_block_invoke + 196
6  UIKit                          0x00000001048a4215 -[UIApplication _handleApplicationLifecycleEventWithScene:transitionContext:completion:] + 349
7  UIKit                          0x000000010488f31a -[UIApplication scene:didUpdateWithDiff:transitionContext:completion:] + 486
8  FrontBoardServices             0x000000010903a2a3 __31-[FBSSerialQueue performAsync:]_block_invoke + 16
9  CoreFoundation                 0x0000000103eb553c __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
10 CoreFoundation                 0x0000000103eab285 __CFRunLoopDoBlocks + 341
11 CoreFoundation                 0x0000000103eaaa43 __CFRunLoopRun + 851
12 CoreFoundation                 0x0000000103eaa486 CFRunLoopRunSpecific + 470
13 GraphicsServices               0x0000000106e6e9f0 GSEventRunModal + 161
14 UIKit                          0x0000000104891420 UIApplicationMain + 1282
15 MyApp                       0x00000001017ac57e top_level_code (CLAppDelegate.swift:16)
16 MyApp                       0x00000001017ac5ba main (CLAppDelegate.swift)
17 libdyld.dylib                  0x0000000106155145 start + 1

The same custom URL scheme is working when opened from anywhere else.

Using Xcode 6.1.1, Deployment target 8.1.

Answer 1

Managed to solve this myself and thought I'll post the solution.

Turns out, the UIApplicationDelegate declaration as auto-completed by one of Xcode's previous versions was incorrect:

func application(application: UIApplication, 
                 openURL url: NSURL, 
                 sourceApplication: String!,   // Wrong
                 annotation: AnyObject?) -> Bool

should really be:

func application(application: UIApplication, 
                 openURL url: NSURL, 
                 sourceApplication: String?,   // OK
                 annotation: AnyObject?) -> Bool

( sourceApplication needs to be String? and NOT String! )

Hope this helps someone.