MultiPatternCatchClauses.swift

enum RocketError: Error {
    case insufficientFuel
    case insufficientAstronauts(needed: Int)
    case noAstronauts(message: String)
    case outOfFuel(message: String)
    case unknownError(message: String)
}


func igniteRockets(fuel: Int, astronauts: Int) throws {
    
    guard astronauts > 0 else {
        throw RocketError.noAstronauts(message: "astronauts can not be in -ve!")
    }
    guard fuel > 0 else {
        throw RocketError.outOfFuel(message: "Rocket is out of fuel!!")
    }

    if fuel < 1000 {
        throw RocketError.insufficientFuel
    } else if astronauts < 3 {
        throw RocketError.insufficientAstronauts(needed: 3)
    } else {
        // Ignite rockets
        print("3... 2... 1... IGNITION!!! LIFTOFF!!!")
    }
}

do {
    try igniteRockets(fuel: 5000, astronauts: -1)
} catch RocketError.insufficientFuel { //OK, earlier as well
    print("The rocket needs more fuel to take off!")
} catch RocketError.insufficientAstronauts(let needed) { //OK, earlier as well
    print("You need at least \(needed) astronauts...")
} catch RocketError.noAstronauts(let message), RocketError.outOfFuel(let message), RocketError.unknownError(let message) { // Also Allowed, Now
    print(message)
}