Question

I am from android background and I just started working on iPhone
I want to perform this operation in iPhone as I do in Android.

ArrayList<String> aa = new ArrayList<String>();

public void fillArray(String s)
{
    aa.add(s);
}

Answer 1

As Binyamin Sharet suggest you have to use NSMutableArray. This class allows you to create a dynamic array. You can perform addition or deletion. On the contrary NSArray is a immutable version of it. You cannot add or delete objects to a NSArray once created.

The same distinction can be applied to NSDictionary and NSMutableDictionary (and other).

Here a simple example.

NSMutableArray* arr = [[NSMutableArray alloc] init];
[arr addObject:@"first string"];
[arr addObject:@"second string"];

An important aspect of NSMutableArray (the same could be applied to other class) is the memory management one. When you add an object to a NSMutableArray it retains objects added to it. So, if you NOT use ARC you have to deal with this aspect.

NSMutableArray* arr = [[NSMutableArray alloc] init];
id obj = [[NSObject alloc] init]; // a general object
[arr addObject:obj];

[obj release];

For further info I suggest you to read about NSMutableArray class reference.

Hope it helps.