Why app crashing while set a value to NSManagedObject in ios - ios

Question

Hi in my application I am setting the value for NSManagedObject while I am trying to set a value app is crashing.Here is the code and error message.
NSManagedObject *object3 = [threadManagedObjectContext objectWithID:[object1 objectID]] ;
for (int i=0;i<[array1 count];i++)
{
NSDictionary *keyValue=[array1 objectAtIndex:i];
[object3 setValue:[[keyValue allValues] lastObject] forKey:[[keyValue allKeys] lastObject]] ;
}
Error: Terminating app due to uncaught exception 'NSGenericException', reason:was mutated while being enumerated
Can any one please help me.

Answer 1

In your code (not the provided) , you're changing a collection while looping/iterating.
Example (not allowed):
for (MyClass *myClassObj in collectionOfMyClass) {
[myClassObj setClassVar: aVar]
}
Solution:
Make a temporary collection of the objects you want to set. Set all of them back outside of your loop.
NSMutableArray *tempArray = [[NSMutableArray alloc] init];
for (MyClass *myClassObj in collectionOfMyClass) {
[tempArray addObject:aVar];
}
[myClassObj setClassVars: tempArray];

Answer 2

You can try below solution for updating the object...
NSManagedObject *object3 = [threadManagedObjectContext objectWithID:[object1 objectID]] ;
int i=0;
for (NSDictionary *keyValue in array1)
{
[[object3 setValue:[[keyValue allValues] lastObject] forKey:[[keyValue allKeys] lastObject]] ;i++;
}
NSError *error;
bool result = [[fetchedResultsController threadManagedObjectContext] save:&error];
if (!result) {
NSLog(#" error saving context, %#, %#", error, error.userInfo);
}
In your code while Looping/Enumerating you are setting value..So it is crashing...!
Hope it helps you....