-[__NSArrayM insertObject:atIndex:]: object cannot be nil' [duplicate] - ios

Question

This question already has answers here:
__NSArrayM insertObject:atIndex:]; object cannot be nil
(2 answers)
Closed 8 years ago.
Here,
NSString *decryptedStr = [[NSString alloc] initWithData:decryptedData encoding:NSUTF8StringEncoding];
"decryptedStr" is getting "decryptedData" has been working fine in simulator.
but
it has not been working fine in iPhone devices. i got an error message is
-[__NSArrayM insertObject:atIndex:]: object cannot be nil'.
plz help me.
this is my code
NSString *stringIndex1 = [[NSString alloc]init];
NSMutableArray *arrAthigaaramList1 = [[NSMutableArray alloc] init];
dictDecryptList=[[NSMutableDictionary alloc]init];
for(int i=0;i<[arrD_Chapter count];i++)//50 Chapter wise
{
stringIndex1 = [arrD_Chapter objectAtIndex:i];
NSData *b64DecData = [Base64 decode:stringIndex1];
NSData *decryptedData = [[NSData alloc]init];
decryptedData= [b64DecData AESDecryptWithPassphrase:#"mypassword"];
NSString *decryptedStr = [[NSString alloc] initWithData:decryptedData encoding:NSUTF32StringEncoding];
if (decryptedStr) {
NSLog(#"Decryped Data Base 64 encoded = %#",decryptedStr);
[arrAthigaaramList1 addObject:decryptedStr];
} else {
NSLog(#"ERROR decrypting!!!");
}
}

Answer 1

change these lines:
NSData *decryptedData = [[NSData alloc]init];
decryptedData= [b64DecData AESDecryptWithPassphrase:#"mypassword"];
NSString *decryptedStr = [[NSString alloc] initWithData:decryptedData encoding:NSUTF32StringEncoding];
to this:
NSData *decryptedData= [b64DecData AESDecryptWithPassphrase:#"mypassword"];
if([decryptedData length] > 0)
{
NSString *decryptedStr = [[NSString alloc] initWithData:decryptedData
encoding:NSUTF32StringEncoding];
} else {
NSLog(#"Hmmm, why is decrypted data a zero byte object??");
}