map(_:_:)
Publishes the values of two key paths as a tuple.
Declaration
func map<T0, T1>(_ keyPath0: KeyPath<Self.Output, T0>, _ keyPath1: KeyPath<Self.Output, T1>) -> Publishers.MapKeyPath2<Self, T0, T1>Parameters
- keyPath0:
The key path of a property on
Output. - keyPath1:
The key path of another property on
Output.
Return Value
A publisher that publishes the values of two key paths as a tuple.
Discussion
In the following example, the map(_:_:) operator uses the Swift key path syntax to access the die1 and die2 members of the DiceRoll structure published by the Just publisher.
The downstream sink subscriber receives only these two values (as an (Int, Int) tuple), not the entire DiceRoll.
struct DiceRoll {
let die1: Int
let die2: Int
}
cancellable = Just(DiceRoll(die1:Int.random(in:1...6),
die2: Int.random(in:1...6)))
.map(\.die1, \.die2)
.sink { values in
print ("Rolled: \(values.0), \(values.1) (total: \(values.0 + values.1))")
}
// Prints "Rolled: 6, 4 (total: 10)" (or other random values).