- (void)discoverUserInfo:(void (^)(CKDiscoveredUserInfo *user))completionHandler {

    [self.container fetchUserRecordIDWithCompletionHandler:^(CKRecordID *recordID, NSError *error) {

        if (error) {
            [self showAlert];
            // In your app, handle this error in an awe-inspiring way.
            NSLog(@"An error occured in %@: %@", NSStringFromSelector(_cmd), error);
            //abort();
        } else {
            [self.container discoverUserInfoWithUserRecordID:recordID
                                           completionHandler:^(CKDiscoveredUserInfo *user, NSError *error) {
                                               if (error) {
                                                   [self showAlert];
                                                   // In your app, handle this error deftly.
                                                   NSLog(@"An error occured in %@: %@", NSStringFromSelector(_cmd), error);
                                                   //abort();
                                               } else {
                                                   dispatch_async(dispatch_get_main_queue(), ^(void){
                                                       completionHandler(user);
                                                   });
                                               }
                                           }];
        }
    }];
}

Exception Type:  EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Triggered by Thread:  0

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   libsystem_kernel.dylib          0x31562df0 0x3154e000 + 85488
1   libsystem_pthread.dylib         0x315e3c92 0x315e0000 + 15506
2   libsystem_c.dylib               0x31501934 0x314b8000 + 301364
3   ForCarl                         0x0006dc1a 0x2f000 + 257050
4   UIKit                           0x2643fcc8 0x26095000 + 3845320
5   UIKit                           0x26748cae 0x26095000 + 7027886
6   UIKit                           0x2643fc64 0x26095000 + 3845220
7   UIKit                           0x26438d88 0x26095000 + 3816840
8   UIKit                           0x26439262 0x26095000 + 3818082
9   UIKit                           0x26379a46 0x26095000 + 3033670
10  UIKit                           0x2637bbd2 0x26095000 + 3042258
11  UIKit                           0x261b4f34 0x26095000 + 1179444
12  UIKit                           0x260d88de 0x26095000 + 276702
13  UIKit                           0x260d84f4 0x26095000 + 275700
14  UIKit                           0x260d840a 0x26095000 + 275466
15  QuartzCore                      0x25abdfe2 0x25aa7000 + 94178
16  libdispatch.dylib               0x3145ec6c 0x3145d000 + 7276
17  libdispatch.dylib               0x3146a54e 0x3145d000 + 54606
18  CoreFoundation                  0x22a09884 0x2293a000 + 850052
19  CoreFoundation                  0x22a07fa4 0x2293a000 + 843684
20  CoreFoundation                  0x2295399c 0x2293a000 + 104860
21  CoreFoundation                  0x229537ae 0x2293a000 + 104366
22  GraphicsServices                0x2a3151a4 0x2a30c000 + 37284
23  UIKit                           0x26104630 0x26095000 + 456240
24  ForCarl                         0x0006d996 0x2f000 + 256406
25  libdyld.dylib                   0x3149caac 0x3149b000 + 6828

Thread 1 name:  Dispatch queue: com.apple.libdispatch-manager
Thread 1:
0   libsystem_kernel.dylib          0x3154f24c 0x3154e000 + 4684
1   libdispatch.dylib               0x3146f4ec 0x3145d000 + 74988
2   libdispatch.dylib               0x3146f21e 0x3145d000 + 74270

Thread 2:
0   libsystem_kernel.dylib          0x3154f49c 0x3154e000 + 5276
1   libsystem_kernel.dylib          0x3154f290 0x3154e000 + 4752
2   CoreFoundation                  0x22a097ee 0x2293a000 + 849902
3   CoreFoundation                  0x22a07db4 0x2293a000 + 843188
4   CoreFoundation                  0x2295399c 0x2293a000 + 104860
5   CoreFoundation                  0x2299d366 0x2293a000 + 406374
6   CoreMotion                      0x23268a26 0x23223000 + 285222
7   libsystem_pthread.dylib         0x315e2de8 0x315e0000 + 11752
8   libsystem_pthread.dylib         0x315e2d5a 0x315e0000 + 11610
9   libsystem_pthread.dylib         0x315e0b04 0x315e0000 + 2820

Thread 3:
0   libsystem_kernel.dylib          0x315639c0 0x3154e000 + 88512
1   libsystem_pthread.dylib         0x315e0e20 0x315e0000 + 3616
2   libsystem_pthread.dylib         0x315e0af8 0x315e0000 + 2808

Thread 4:
0   libsystem_kernel.dylib          0x315639c0 0x3154e000 + 88512
1   libsystem_pthread.dylib         0x315e0e20 0x315e0000 + 3616
2   libsystem_pthread.dylib         0x315e0af8 0x315e0000 + 2808

Thread 5:
0   libsystem_kernel.dylib          0x315639c0 0x3154e000 + 88512
1   libsystem_pthread.dylib         0x315e0e20 0x315e0000 + 3616
2   libsystem_pthread.dylib         0x315e0af8 0x315e0000 + 2808

Thread 6:
0   libsystem_kernel.dylib          0x315639c0 0x3154e000 + 88512
1   libsystem_pthread.dylib         0x315e0e20 0x315e0000 + 3616
2   libsystem_pthread.dylib         0x315e0af8 0x315e0000 + 2808

Thread 0 crashed with ARM Thread State (32-bit):
    r0: 0x00000000    r1: 0x00000000      r2: 0x00000000      r3: 0x00000004
    r4: 0x00000006    r5: 0x33ea39dc      r6: 0x00000000      r7: 0x001fda68
    r8: 0x00000000    r9: 0x33ea39dc     r10: 0x00000001     r11: 0xc2000000
    ip: 0x00000148    sp: 0x001fda5c      lr: 0x315e3c97      pc: 0x31562df0
  cpsr: 0x00000010

Binary Images: