Question

In this code from an array i am selecting a dictionary,modifying it and saving back in another array .but i dont know why at the second last line of this code ie where i am inserting the dict it is crashing (message sent to deallocated instance).how can i fix this

        NSArray *array=[NSArray arrayWithContentsOfFile:plistPath];
        NSLog(@"array before %@",array);
        NSMutableArray *tempArray=[[NSMutableArray alloc]init];
        tempArray=(NSMutableArray*)array;
        NSMutableDictionary *dictToBeChanged=[[NSMutableDictionary alloc]init];
        dictToBeChanged=[tempArray objectAtIndex:indexPath.row];
        [dictToBeChanged setObject:[NSNumber numberWithBool:YES] forKey:@"isPaid"];
        [tempArray removeObjectAtIndex:indexPath.row];
        [tempArray insertObject:dictToBeChanged atIndex:indexPath.row];
        NSLog(@"array after %@",tempArray);

Answer 1

When you assign array to tempArray you don’t make it mutable just because you cast it.

It’s an NSArray, so you can’t add/remove its objects.

Also, there are a few unneeded initializations (of tempArray and dictToBeChanged) since you’re overwriting those variables with something else right after initializing (thus creating leaks).

What you need is probably something like this:

NSMutableArray *array = [NSMutableArray arrayWithContentsOfFile:plistPath];
NSMutableDictionary *dictToBeChanged = [[[array objectAtIndex:indexPath.row] mutableCopy] autorelease];
[dictToBeChanged setObject:[NSNumber numberWithBool:YES] forKey:@"isPaid"];
[array replaceObjectAtIndex:indexPath.row withObject:dictToBeChanged];

Note that this code doesn’t do any validations on the contents of your plist.