Swift15 - Nil-Coalescing Operator

Nil-Coalescing Operator

The nil-coalescing operator (a ?? b) unwraps an optional a if it contains a value, or returns a default value b if a is nil. The expression a is always of an optional type. The expression b must match the type that is stored inside a.

 

nil 병합 연산자란

- Optional ?? Value

- 옵셔널 값이 nil이 아니면 해당 값 반환, 옵셔널 값이 nil이면 오른쪽 값 반환

var optionalVal1: String? = nil
var optionalVal2: String? = "hello"

var res1 = optionalVal1 ?? "Nil-Coalescing"
var res2 = optionalVal2 ?? "Operator"

print(res1) // "Nil-Coalescing"
print(res2) // "hello"