iOS 5 Programming Cookbook

1.9. Comparing Values in Objective-C with an If Statement

Problem

You want to compare two values in Objective-C.

Solution

Use if statements. Please refer to the Discussion section of this recipe for more information about different scenarios under which you might want to use if statements.

Discussion

We use if statement in our everyday conversations. For instance, you might say “If I get a hold of him, I’ll tell him...” or “I would put the computer to sleep if it didn’t take so long to come back up”. All these statements have a condition. If statements in Objective-C also have a condition. You can even make them more sophisticated, having your app do something if a condition is met and something else if the condition is not met. The basic form of an if statement is:

if (<replaceable>condition</replaceable>){
  /* Your code to get executed if the <replaceable>condition</replaceable> is met */
}

Note

As long as the condition is a value other than zero/nil/NULL, the code inside the if statement will run.

An if statement that has an “otherwise” clause in it is known as an if-else statement, and its format is:

if (<replaceable>condition</replaceable>){
  /* Your code to get executed if the <replaceable>condition</replaceable> is met */
} else {
  /* Code to get executed if <replaceable>condition</replaceable> is not met */
}

The else clause of the if-else statement can also contain its own if statement! That might sound strange, but consider this scenario. In real life, you can say something similar ...