NSUserDefaults setObject method causes the app to crash in ios8 - ios

Question

I am having an app in which I am passing some data between viewControllers with NSUserDefaults.
This is the code below I am using.
[[NSUserDefaults standardUserDefaults]setObject:selectedLists forKey:UserID];
Where selectedLists is NSMutableArray and UserID is NSString.
This code works fine until ios7 and xCode5.
Since I have updated xCode6 and now I am using ios8, my app works fine with xCode 6 and ios 7.1 but the app crashes when I run the app in ios8 devices with the error below.
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFNumber length]: unrecognized selector sent to instance 0x7a027060'
I just don't understand what is the problem here.
If anyone has faced this problem with ios8 then please help me.
Thanks in advance.
Value of selectedLists
{
CardFace = Word;
ImportFlag = Import;
ListID = 1;
ListName = "Adjectives - Appearance";
QuizBy = Definition;
UserID = 1;
}
and UserId is 1.
EDITED
*** First throw call stack:
(
0 CoreFoundation 0x06a24df6 __exceptionPreprocess + 182
1 libobjc.A.dylib 0x03ac8a97 objc_exception_throw + 44
2 CoreFoundation 0x06a2ca75 -[NSObject(NSObject) doesNotRecognizeSelector:] + 277
3 CoreFoundation 0x069759c7 ___forwarding___ + 1047
4 CoreFoundation 0x0697558e _CF_forwarding_prep_0 + 14
5 CoreFoundation 0x068df30f CFStringGetLength + 143
6 CoreFoundation 0x069de510 _CFPrefsEncodeKeyValuePairIntoMessage + 64
7 CoreFoundation 0x06a275cf -[CFPrefsPlistSource sendMessageSettingValue:forKey:] + 111
8 CoreFoundation 0x06954f3a -[CFPrefsPlistSource alreadylocked_setValue:forKey:] + 250
9 CoreFoundation 0x06954e22 -[CFPrefsSource setValue:forKey:] + 82
10 CoreFoundation 0x06954dc3 ___CFPreferencesSetValueWithContainer_block_invoke + 51
11 CoreFoundation 0x0690ef0a +[CFPrefsSource withSourceForIdentifier:user:byHost:container:perform:] + 1274
12 CoreFoundation 0x06954d61 _CFPreferencesSetValueWithContainer + 225
13 CoreFoundation 0x06a0aa62 _CFPreferencesSetAppValueWithContainer + 66
14 Foundation 0x0347f53f -[NSUserDefaults(NSUserDefaults) setObject:forKey:] + 59
15 Foundation 0x0353eeba -[NSUserDefaults(NSKeyValueCoding) setValue:forKey:] + 68
16 Vocab 0x000eaecc Vocab + 720588
17 libobjc.A.dylib 0x03ade7cd -[NSObject performSelector:withObject:withObject:] + 84
18 UIKit 0x022a079d -[UIApplication sendAction:to:from:forEvent:] + 99
19 UIKit 0x022a072f -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 64
20 UIKit 0x023d3a16 -[UIControl sendAction:to:forEvent:] + 69
21 UIKit 0x023d3e33 -[UIControl _sendActionsForEvents:withEvent:] + 598
22 UIKit 0x023d309d -[UIControl touchesEnded:withEvent:] + 660
23 UIKit 0x022f0aba -[UIWindow _sendTouchesForEvent:] + 874
24 UIKit 0x022f1595 -[UIWindow sendEvent:] + 791
25 UIKit 0x022b6aa9 -[UIApplication sendEvent:] + 242
26 UIKit 0x022c68de _UIApplicationHandleEventFromQueueEvent + 20690
27 UIKit 0x0229b079 _UIApplicationHandleEventQueue + 2206
28 CoreFoundation 0x069487bf __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
29 CoreFoundation 0x0693e2cd __CFRunLoopDoSources0 + 253
30 CoreFoundation 0x0693d828 __CFRunLoopRun + 952
31 CoreFoundation 0x0693d1ab CFRunLoopRunSpecific + 443
32 CoreFoundation 0x0693cfdb CFRunLoopRunInMode + 123
33 GraphicsServices 0x0436424f GSEventRunModal + 192
34 GraphicsServices 0x0436408c GSEventRun + 104
35 UIKit 0x0229ee16 UIApplicationMain + 1526
36 Vocab 0x0004c9bc Vocab + 72124
37 libdyld.dylib 0x03ee6ac9 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
Edited
On my tableview's didselect method...
UserID = [[users objectAtIndex:indexPath.row] valueForKey:#"UserID"];
where users is an array.

Answer 1

You should check the UserID type because crash is not related with changing NSArray to NSMutableArray.
You must be confusing NSNumber with NSString on your userID:
Change your code and instead of userID use the variable userIDString
NSString userIDString;
//If UserID is class of NSNumber turn its value to NSString
if ([UserID isKindOfClass:[NSNumber class]])
{
userIDString = [UserID stringValue];
}
else
userIDString = UserID ;

Answer 2

During runtime UserId is probably of type NSNumber, even if in your code it is typed NSString.
Check how UserId is created. Use the debugger to check the runtime type.
The newly posted code shows that your retrieve the UserId from the users array which probably consists of dictionaries. In those dictionaries there's a value for the key UserID. It depends on how the array of dictionaries is created (json deserialization?) but it seems that the type of object referred to by the UserID key is a number type, not a string. So all you have to do is convert this number into a string:
UserID = [[[users objectAtIndex:indexPath.row] valueForKey:#"UserID"] stringValue];
Now your key is always a string.

Answer 3

Try to encode your data in NSData and save it in NSUserDefaults and retrieved back, once needed. Have a look at this thread and this one.

Answer 4

Should not use NSUSerdefault to keep a collection of custom objects.
You should save them using NSkeyedUnarchiver/NSkeyedarchiver.
Ref: NSCoding.

Answer 5

I think can't store NSMutableArrays in NSUserDefaults since iOS8 (according to different posts). Try casting it into an array before (or create a new one).
Like this for example :
NSArray *arr = [NSArray arrayWithArray:selectedLists];
And store arr in NSUserDefaults.