How to replace an object in MSMutableArray with another object

Question

OK. I've spent a ridiculous amount of time on this. I've looked all around on the internet to the point of feeling pretty stupid. I have program which is an array of x, 2, "+". So I make a copy of program and try to replace x with its value (5) from variableValues.

Can anyone tell me how in the world to do this?

+ (double)runProgram:(id)program usingVaraiableValues:(NSDictionary *)variableValues {

    NSMutableArray *program2 = program;
    for (NSString *obj in program) {
        NSNumber *number = [variableValues objectForKey:obj];
        if (number) {
            int index = [program indexOfObject:obj];
            NSLog(@"index = %i", index);
            [program2 replaceObjectAtIndex:index withObject:number];
        }
    }
    return [self runProgram:program2];
}

program2 = program doesn't make a copy, much less a mutable one. — Kevin
– Kevin, Commented Jul 5, 2013 at 3:30

leoformaggio · Accepted Answer · 2013-07-05 03:30:31Z

1

Actually program2 isn't a copy of program, it is a reference to the same memory address. Try doing NSMutableArray *program2 = [program mutableCopy]; instead.

answered Jul 5, 2013 at 3:30

leoformaggio

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5 Comments

lnafziger Over a year ago

This probably won't work since program is of type id. :-P

leoformaggio Over a year ago

Ok, maybe, but not probably. Furthermore, if program isn't a NSArray, this line probably won't work too int index = [program indexOfObject:obj];.

lnafziger Over a year ago

Yeah, the problem though, is that the compiler won't recognize the id as accepting the message mutableCopy. It needs to be cast to an NSArray...

lnafziger Over a year ago

Or better yet, just change the signature of the method so that it requires an array. That way we always know what we are getting. :)

Patricia Over a year ago

Thank you, guys. I wish I could add points. You both are great!!

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