How to check for Nil

Question

I am currently studying objective-c and the basic c programming language.

I have a questions about a particular line of code:

if (!balance)

Answer 1

In Objective-C, nil is roughly analogous to 0, NULL or false, but for object pointers. In an if statement, it will behave the same as one of the aforementioned scalar values. For example, the following two if statements should produce the same results:

NSNumber *balance = nil;

if (!balance) {
    // do something if balance is nil
}

if (balance == nil) {
    // do something if balance is nil
}