Crash in openURL: Possible Facebook SDK bug in iOS 9

Question

Context

I am using the FBSDKLoginButton with my app. I am on Xcode 7.0 and my iPhone is running iOS 9 beta 3. I followed every step showed by Facebook (creating the app, etc) and followed the steps for adding the button as in https://developers.facebook.com/docs/facebook-login/ios#login-button.

As I am on iOS 9, I had to add some minor changes to the info.plist file to enable cross-app opening:

<key>LSApplicationQueriesSchemes</key>
<array>
    <string>fbauth</string>
</array>

and since the openURL method from UIAppDelegate changed on iOS9,I changed the openURL code snippet Facebook provides from this:

func application(application: UIApplication,
    openURL url: NSURL,
    sourceApplication: String?,
    annotation: AnyObject?) -> Bool {
        return FBSDKApplicationDelegate.sharedInstance().application(
            application,
            openURL: url,
            sourceApplication: sourceApplication,
            annotation: annotation)
}

to this:

func application(app: UIApplication, openURL url: NSURL, options: [String : AnyObject]) -> Bool
{
        return FBSDKApplicationDelegate.sharedInstance().application(
            app,
            openURL: url,
            sourceApplication: options["UIApplicationOpenURLOptionsSourceApplicationKey"] as? String,
            annotation: nil)
}

---

Issue & Question So my issue here is that even though everything works perfectly (I mean the whole login button process plus getting user data from the Facebook graph) when I run the app from the simulator or directly on my iPhone from XCode, I do have a problem when I run the same process with my application but this time installed from an archive. I have tried either from an OTA app or an app installed with the Xcode organizer using the archive's IPA file. In both case I get a crash when Facebook returns back to my app. Since I cannot be using Xcode's debugger all I have is a crash log.

Incident Identifier: 842E980C-8DE0-485F-8B3E-8CD889D34B3B
CrashReporter Key:   3e77866746471e437b9174c6082fc9136a18514f
Hardware Model:      iPhone7,2
Process:             Process Name [1086]
Path:                /private/var/mobile/Containers/Bundle/Application/AA43C098-DFC0-483C-A073-C2401078E9FC/Some App.app/someapp
Identifier:          fr.someapp.Some-App
Version:             1 (1.0)
Code Type:           ARM-64 (Native)
Parent Process:      launchd [1]

Date/Time:           2015-07-19 20:18:41.41 +0200
Launch Time:         2015-07-19 20:18:35.35 +0200
OS Version:          iOS 9.0 (13A4293g)
Report Version:      105

Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000001, 0x000000010005f6e4
Triggered by Thread:  0

Filtered syslog:
None found

Global Trace Buffer (reverse chronological seconds):
0.228132     AppleJPEG                  0x000000018dba5008 [0x13e871e00] Decoding completed without errors
0.250546     AppleJPEG                  0x000000018dba31a0 [0x13e871e00] Options: 1080x1920 [FFFFFFFF,FFFFFFFF] 00025060
0.250629     AppleJPEG                  0x000000018dba3058 [0x13e871e00] Decoding: C0 0x04380780 0x0044304A 0x22111100 0x00000000 175592
0.256474     AppleJPEG                  0x000000018dba5008 [0x13e867200] Decoding completed without errors
0.261051     AppleJPEG                  0x000000018dba31a0 [0x13e867200] Options: 750x1334 [FFFFFFFF,FFFFFFFF] 00025060
0.261101     AppleJPEG                  0x000000018dba3058 [0x13e867200] Decoding: C0 0x02EE0536 0x002F304A 0x22111100 0x00000000 75882
0.262141     AppleJPEG                  0x000000018dba5008 [0x13e85c600] Decoding completed without errors
0.272075     AppleJPEG                  0x000000018dba31a0 [0x13e85c600] Options: 750x1334 [FFFFFFFF,FFFFFFFF] 00025060
0.272281     AppleJPEG                  0x000000018dba3058 [0x13e85c600] Decoding: C0 0x02EE0536 0x002F304A 0x22111100 0x00000000 108826
0.273070     AppleJPEG                  0x000000018dba5008 [0x13f04bc00] Decoding completed without errors
0.283798     AppleJPEG                  0x000000018dba31a0 [0x13f04bc00] Options: 750x1334 [FFFFFFFF,FFFFFFFF] 00025060
0.283798     AppleJPEG                  0x000000018dba3058 [0x13f04bc00] Decoding: C0 0x02EE0536 0x002F304A 0x22111100 0x00000000 72967
5.783070     CFNetwork                  0x0000000186041d44 TCP Conn 0x13e5a1b90 SSL Handshake DONE
5.874750     CFNetwork                  0x0000000186041c54 TCP Conn 0x13e5a1b90 starting SSL negotiation
5.875481     CFNetwork                  0x00000001860e0e14 TCP Conn 0x13e5a1b90 complete. fd: 6, err: 0
5.876954     CFNetwork                  0x00000001860e21e4 TCP Conn 0x13e5a1b90 event 1. err: 0
5.984181     CFNetwork                  0x00000001860e22f8 TCP Conn 0x13e5a1b90 started
5.992333     CFNetwork                  0x0000000186137140 Creating default cookie storage with default identifier
5.992333     CFNetwork                  0x000000018613710c Faulting in CFHTTPCookieStorage singleton
5.992562     CFNetwork                  0x0000000186188068 Faulting in NSHTTPCookieStorage singleton
6.189612     AppleJPEG                  0x000000018dba234c [0x13e871e00] Created session
6.190797     AppleJPEG                  0x000000018dba234c [0x13e867200] Created session
6.192109     AppleJPEG                  0x000000018dba234c [0x13e85c600] Created session
6.197484     AppleJPEG                  0x000000018dba234c [0x13f04bc00] Created session



Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   Some app                        0x000000010005f6e4 function signature specialization <Arg[0] = Owned To Guaranteed, Arg[1] = Owned To Guaranteed, Arg[2] = Owned To Guaranteed and Exploded, Arg[3] = Dead> of Some_App.AppDelegate.application (Some_App.AppDelegate)(ObjectiveC.UIApplication, openURL : ObjectiveC.NSURL, options : [Swift.String : Swift.AnyObject]) -> Swift.Bool (AppDelegate.swift:100)
1   Some_app                        0x000000010005e7a8 @objc Some_App.AppDelegate.application (Some_app.AppDelegate)(ObjectiveC.UIApplication, openURL : ObjectiveC.NSURL, options : [Swift.String : Swift.AnyObject]) -> Swift.Bool (AppDelegate.swift:0)
2   UIKit                           0x000000018c1ee664 0x18bf34000 + 2860644
3   UIKit                           0x000000018c1ee168 0x18bf34000 + 2859368
4   UIKit                           0x000000018c1f5c30 0x18bf34000 + 2890800
5   UIKit                           0x000000018c1fb644 0x18bf34000 + 2913860
6   UIKit                           0x000000018c1fa9dc 0x18bf34000 + 2910684
7   UIKit                           0x000000018c1e6fd4 0x18bf34000 + 2830292
8   UIKit                           0x000000018c1e6eb4 0x18bf34000 + 2830004
9   FrontBoardServices              0x00000001905ffbe0 0x1905d8000 + 162784
10  FrontBoardServices              0x00000001905fff60 0x1905d8000 + 163680
11  CoreFoundation                  0x00000001868eb8b4 0x18680c000 + 915636
12  CoreFoundation                  0x00000001868eb348 0x18680c000 + 914248
13  CoreFoundation                  0x00000001868e901c 0x18680c000 + 905244
14  CoreFoundation                  0x00000001868157fc 0x18680c000 + 38908
15  GraphicsServices                0x00000001918a316c 0x191898000 + 45420
16  UIKit                           0x000000018bfae5e4 0x18bf34000 + 501220
17  Some app                        0x000000010005eaa4 main (AppDelegate.swift:14)
18  libdyld.dylib                   0x000000019bb128b4 0x19bb10000 + 10420

It seems that when Facebook calls back my app the crash occurs in the openURL method of my AppDelegate. As mentioned above there are two ways to code this method as of iOS9 and I tried both. If I remove the Facebook code inside the method then I do not crash but I do not log In. So the line that crashes is Facebook's line. And it only crashes if my app was installed from an archive. Any ideas? Maybe Facebook's SDK has a bug on this particular case?

Answer 1

I have found my answer

Looks like it was a Release Mode only issue. By enabling Xcode to run Release builds I was able to debug my issue. It was caused by the parameter sourceApplication that apparently needs to be unwrapped when in release mode. No idea why, but at least I got it to work.

func application(app: UIApplication, openURL url: NSURL, options: [String : AnyObject]) -> Bool
{
        return FBSDKApplicationDelegate.sharedInstance().application(
            app,
            openURL: url,
            sourceApplication: options["UIApplicationOpenURLOptionsSourceApplicationKey"] as! String,
            annotation: nil)
}