Who has used Xamarin for iOS applications? The program works well in the simulator and IPhone 5s, but crashes on IPhone 4s. How to win?

Question

Xamarin

Here's what's in the Device Log:

Incident Identifier: E410D1BD-AA95-4329-9D5D-6347BD28D4B3
CrashReporter Key:   8b4a3be95daeb058f1b81ff655e4c6adac20f533
Hardware Model:      iPhone3,1
Process:             Food30_2 [2961]
Path:                /var/mobile/Applications/EC28ED85-259A-4EE4-83EA-8705161E5B39/Food30_2.app/Food30_2
Identifier:          food302
Version:             1.0 (1.0)
Code Type:           ARM (Native)
Parent Process:      launchd [1]

Date/Time:           2014-07-05 16:16:44.739 +0400
OS Version:          iOS 7.1.1 (11D201)
Report Version:      104

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

Thread 0 Crashed:
0   libsystem_kernel.dylib        	0x385b61f0 __pthread_kill + 8
1   libsystem_pthread.dylib       	0x38620792 pthread_kill + 54
2   libsystem_c.dylib             	0x38566fd8 abort + 72
3   Food30_2                      	0x003e4cc8 mono_handle_native_sigsegv (mini-exceptions.c:2341)
4   Food30_2                      	0x003e99ba sigabrt_signal_handler (mini-posix.c:206)
5   libsystem_platform.dylib      	0x3861af90 _sigtramp + 40
6   libsystem_pthread.dylib       	0x38620792 pthread_kill + 54
7   libsystem_c.dylib             	0x38566fd8 abort + 72
8   Food30_2                      	0x0048ada4 monotouch_unhandled_exception_handler (monotouch-glue.m:1562)
9   Food30_2                      	0x003e509c mono_invoke_unhandled_exception_hook (mini-exceptions.c:2670)
10  Food30_2                      	0x003f0702 mono_thread_abort_dummy (mini.c:2821)
11  Food30_2                      	0x003e4a56 mono_handle_exception_internal (mini-exceptions.c:1697)
12  Food30_2                      	0x003e3ade mono_handle_exception (mini-exceptions.c:1921)
13  Food30_2                      	0x003de2d0 mono_arm_throw_exception (exceptions-arm.c:157)
14  Food30_2                      	0x0024e698 throw_exception + 64
15  Food30_2                      	0x000b8dd8 Food30_2__Food30_2_DataBase_GetFoods_Food30_2_Criteria + 928
16  Food30_2                      	0x000d5e58 Food30_2.FoodManager:GetFoods (FoodManager.cs:316)
17  Food30_2                      	0x000b10ae p_993_plt_Food30_2_PagesController__ctor_Food30_2_TabController_Food30_2_Criteria_llvm + 46
18  Food30_2                      	0x000cea0c Food30_2.TabController:.ctor (TabController.cs:37)
19  Food30_2                      	0x000ce7d0 Food30_2.AppDelegate:FinishedLaunching (AppDelegate.cs:72)
20  Food30_2                      	0x00234b4c wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr_0 + 196
21  Food30_2                      	0x003effae mono_jit_runtime_invoke (mini.c:6716)
22  Food30_2                      	0x0042d6ca mono_runtime_invoke (object.c:2828)
23  Food30_2                      	0x003bc7dc native_to_managed_trampoline_1 (<stdin>:45)
24  Food30_2                      	0x003bef10 -[AppDelegate application:didFinishLaunchingWithOptions:] (<stdin>:1052)
25  UIKit                         	0x300d05a2 -[UIApplication _handleDelegateCallbacksWithOptions:isSuspended:restoreState:] + 270
26  UIKit                         	0x300cfef6 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 1606
27  UIKit                         	0x300ca586 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 710
28  UIKit                         	0x30066704 -[UIApplication handleEvent:withNewEvent:] + 3536
29  UIKit                         	0x3006586c -[UIApplication sendEvent:] + 68
30  UIKit                         	0x300c9cc4 _UIApplicationHandleEvent + 612
31  GraphicsServices              	0x3267eaea _PurpleEventCallback + 606
32  GraphicsServices              	0x3267e6d2 PurpleEventCallback + 30
33  CoreFoundation                	0x2d80fab4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 32
34  CoreFoundation                	0x2d80fa4e __CFRunLoopDoSource1 + 342
35  CoreFoundation                	0x2d80e222 __CFRunLoopRun + 1394
36  CoreFoundation                	0x2d778f0a CFRunLoopRunSpecific + 518
37  CoreFoundation                	0x2d778cee CFRunLoopRunInMode + 102
38  UIKit                         	0x300c8eec -[UIApplication _run] + 756
39  UIKit                         	0x300c4168 UIApplicationMain + 1132
40  Food30_2                      	0x00171620 (wrapper managed-to-native) MonoTouch.UIKit.UIApplication:UIApplicationMain + 268
41  Food30_2                      	0x001392fe monotouch__MonoTouch_UIKit_UIApplication_Main_string___string_string + 146
42  Food30_2                      	0x000b101a Food30_2__Food30_2_Application_Main_string__ + 18
43  Food30_2                      	0x00234b4c wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr_0 + 196
44  Food30_2                      	0x003effae mono_jit_runtime_invoke (mini.c:6716)
45  Food30_2                      	0x0042d6ca mono_runtime_invoke (object.c:2828)
46  Food30_2                      	0x0043131e mono_runtime_exec_main (object.c:4085)
47  Food30_2                      	0x0043115e mono_runtime_run_main (object.c:3711)
48  Food30_2                      	0x003de0f8 mono_jit_exec (driver.g.c:1009)
49  Food30_2                      	0x0047932c main (main.m:486)
50  libdyld.dylib                 	0x38500ab4 start + 0

Thread 1:
0   libsystem_kernel.dylib        	0x385a3808 kevent64 + 24
1   libdispatch.dylib             	0x384efde8 _dispatch_mgr_invoke + 228
2   libdispatch.dylib             	0x384def6e _dispatch_mgr_thread$VARIANT$up + 34

Thread 2:
0   libsystem_kernel.dylib        	0x385b6c70 __workq_kernreturn + 8
1   libsystem_pthread.dylib       	0x3861dbda _pthread_wqthread + 306
2   libsystem_pthread.dylib       	0x3861da94 start_wqthread + 4

Thread 3:
0   libsystem_kernel.dylib        	0x385b6c70 __workq_kernreturn + 8
1   libsystem_pthread.dylib       	0x3861dbda _pthread_wqthread + 306
2   libsystem_pthread.dylib       	0x3861da94 start_wqthread + 4

Thread 0 crashed with ARM Thread State (32-bit):
    r0: 0x00000000    r1: 0x00000000      r2: 0x00000000      r3: 0x27d562bc
    r4: 0x00000006    r5: 0x3a31d18c      r6: 0x16a0fac0      r7: 0x27d562b4
    r8: 0x16a0fa00    r9: 0x3861af69     r10: 0x00635f39     r11: 0x00635f29
    ip: 0x00000148    sp: 0x27d562a8      lr: 0x38620797      pc: 0x385b61f0
  cpsr: 0x00000010

Binary Images:
0xaa000 - 0x64dfff Food30_2 armv7  <0c62212053d13320852c22a6e08ac966> /var/mobile/Applications/EC28ED85-259A-4EE4-83EA-8705161E5B39/Food30_2.app/Food30_2
0x2bed8000 - 0x2bef8fff dyld armv7  <651a31c39f71311f965f8ac44de02c88> /usr/lib/dyld
0x2c808000 - 0x2c808fff Accelerate armv7  <0424978b39f037a7b3bf9aad5b34a5b3> /System/Library/Frameworks/Accelerate.framework/Accelerate
0x2c812000 - 0x2c9defff vImage armv7  <c4834965bdc638fcb1082f53a7721f42> /System/Library/Frameworks/Accelerate.framework/Frameworks/vImage.framework/vImage
0x2c9df000 - 0x2cab8fff libBLAS.dylib armv7  <cfc693306499378c9c09851259cf3563> ...

Answer 1

It only crashed on IPhone 4, IOS 7.1.1, I commented out the data access layer and everything worked without data. Rewriting the data layer.

Answer 2

Can you show what you have in AppDelegate ApplicationDidFinishLaunching()? Falls, as I understand it, at the start?