What is the default value of a basic Boolean in Swift?

Question

I want to know about Bool in Swift.

If Bool is a basic primitive datatype, why is a Boolean's default value nil?

var test: Bool!
print(test) // nil

In Java the Boolean default value is false:

Default value of 'boolean' and 'Boolean' in Java

Answer 1

Bool, Bool! and Bool? all are different in Swift.

1. Bool is a non-optional data type that can have values - true/false. You need to initialize it in the initializer or while declaring it before using it.

var x : Bool = false

var x: Bool
init()
{
   x = false
}

2. Bool? is an optional data type that can have values - nil/true/false. In order to use this type, you need to unwrap it using if let or force unwrapping.

var x: Bool?

if let value = x
{
   //TODO: use value instead of x
}

3. Bool! is an implicitly unwrapped optional data type that can have values - nil/true/false. The difference here is it must contain a value before using it else it will result in runtime exception. Since it is implicitly unwrapped, no need to unwrap it using if let or force unwrapping.

var x: Bool! //Must contain value before using