Choosing between guard statement and if let

Swift offers two important features for handling optionals: the guard statement and if let, also known as optional binding.

What is guard?

The guard statement is ideal for scenarios where you want to ensure certain conditions are met before proceeding with the execution of your code. If these conditions are not met, the guard statement allows for an early exit, preventing further code execution that would likely fail or produce incorrect results.

For example, consider a situation where you’re making a network request. Before sending off the request, you use a guard statement to check if the request object itself is not nil. Discovering that the request is nil at this early stage allows you to exit the function before attempting the network call, which would inevitably fail due to the absence of a valid request.

func sendNetworkRequest() {
  guard let request = buildRequest() else {
    print("Invalid request. Exiting function.")
    return
  }
// Proceed with a valid request
}

What is if let?

The if let statement in Swift is used for optional binding. It provides a safe way to check for and unwrap the value of an optional only if it contains a value, thereby avoiding the risk of runtime errors associated with unwrapping a nil optional. This technique is particularly useful when you are uncertain if an optional contains a value and you want to execute a block of code only if it does.

Consider you are working with a dictionary of user information where the value for each key is optional because some information might be missing. You want to access the user’s age, but since it’s an optional, you need to safely unwrap it:

let userInfo: [String: Any?] = ["name": "Ravi", "age": 30]

if let age = userInfo["age"] as? Int {
   print("User's age is \(age).")
} else {
  print("User's age is not available.")
}

In the above code, we are ensuring that only when you are able to retrieve the value from userInfo you are printing the age. Instead Optional Binding if you try to force unwrap the value and if the age is not present then app will crash. Thus optional binding offers to safer ways to handle Optionals in Swift.