Mastering Swift 2

The need for optional types in Swift

Now, the burning question is why does Swift need optionals? To understand why Swift has optionals, we should examine what problems optionals are designed to solve.

In most languages, it is possible to create a variable without giving it an initialized value. For example, in Objective-C, both lines of code are valid:

int i;
MyObject *m;

Now, let's say that the MyObject class has the following method:

-(int)myMethodWithValue:(int)i {
    return i*2;
}

This method takes the value passed in from the i parameter, multiplies it by 2, and returns the results. Let's try to call this method using the following code:

MyObject *m;
NSLog(@"Value: %d",[m myMethodWithValue:5]);

Our first thought might be that this code would display ...