if let vs guard let : Swift

In Swift, both if let and guard let are used to safely unwrap optional values. However, there are some differences between the two.

The syntax for if let is:

if let unwrappedValue = optionalValue {
    // code to execute when unwrapping is successful
} else {
    // code to execute when unwrapping fails
}

The syntax for guard let is:

guard let unwrappedValue = optionalValue else {
    // code to execute when unwrapping fails
    return
}

1. Use case: if let is typically used when you need to execute code only if the optional value is not nil. It is useful for optional chaining, unwrapping optional bindings, and checking for nil values. guard let is typically used when you need to exit a function or method early if the optional value is nil. It is useful for checking input parameters or unwrapping multiple optional values.
2. Scope: The unwrapped value in an if let statement is only available within the scope of the if statement, whereas the unwrapped value in a guard let statement is available for the rest of the enclosing block.
3. Return type: if let can return a value from the block it is used in, while guard let cannot. guard let requires that you exit the enclosing function or block using a return, break, continue, or throw.

In summary, if let is used when you want to conditionally execute code, while guard let is used when you want to ensure a value is not nil before proceeding with the rest of the block of code.