Swift - Nil coalescing operator
The Swift nil-coalescing operator (a ?? b) returns right-hand side operand when left-hand side operand is nil, otherwise returns left-hand side operand. The expression a is always of an optional type. The expression b must match the type that is stored in a.
Please note that If the value of a is non-nil, the value of b is not evaluated. This is known as short-circuit evaluation.
The example below shows how to use nil-coalescing operator to choose between a default color and an optional user-defined color.
//defaults to nil var AppColor: String? var DefaultColor = "Blue" print("Color of App = \(AppColor ?? DefaultColor)")
The output of the above code will be:
Color of App = Blue
❮ Swift - Operators