Optionals, unwrap, and force unwrap

In the real world, we don't always know the answer to a problem, and problems can occur if we blindly assume that someone does. The same is true in programming languages, especially when dealing with external systems that we may not control. In many languages, including Objective-C (until recently), there was no way to indicate that something being declared may not exist at the time you attempt to access it. This would lead to either fragile code that could have broken if a nil unexpectedly found its way in or tests being run all over the code to ensure that a value did exist where it was needed, which added complexity and increased the boilerplate code that had to be written.

With a focus on Swift being type-safe and making it easier to write safe code, this ambiguity had to be addressed, and the Swift language does this with the use of optionals.