Swift provides type checking and type casting. We can check the type of a variable with the is keyword. It is most commonly used in if statements, as shown in the following code:
let aConstant = "String"
if aConstant is String {
print("aConstant is a String")
} else {
print("aConstant is not a String")
}As String is a value type and the compiler can infer the type, the Swift compiler will issue a warning because it already knows that aConstant is String. Another example can be the following, where we check whether anyString is String:
let anyString: Any = "string"
if anyString is String {
print("anyString is a String")
} else {
print("anyString is not a String")
}Using the is operator is useful to check the type of a class instance, specifically, the ones that have subclasses. We can use the is operator to determine if an object is an instance of a specific class.
Similarly, we can use the as operator to actually coerce an object to a type...