in swift assert(0) Cannot convert value of type Int to expected argument type Bool

Question

I am translating objective -C to swift, but I get error when I write assert(0) in swift, the error message is "in swift assert(0) Cannot convert value of type Int to expected argument type Bool "

my code in objective -c:

switch ([[UIApplication sharedApplication] applicationState]) {
        case UIApplicationStateActive:
            [statusStr appendString:@"foreground"];
            break;
        case UIApplicationStateInactive:
            [statusStr appendString:@"inactive"];
            break;


        case UIApplicationStateBackground:
            [statusStr appendString:@"background"];
            break;

        default:
            assert(0);
            break;
    }

and translate in swift :

 switch UIApplication.shared.applicationState {

            case .active:
                statusStr += "foreground"
            case .inactive:
                statusStr += "inactive"
            case .background:
                statusStr += "background"
            default:
                assert(0)
                break

            }

I don't know 0 mean in swift make it assert(true) or assert(false).

Thanks in advance.

What do you not understand about the error message, it is as clear as it gets. assert expects a Bool, you give it an Int. That does not work. Do `assert(false)`, whatever that is supposed to do. — luk2302, May 17 '17 at 08:41
Just try `assert(true)` and `assert(false)` ... which one fires? — Martin R, May 17 '17 at 08:41
@InderKumarRathore: You don't have to tell *me* :) It was suggestion to OP. — Martin R, May 17 '17 at 08:42
Btw., `fatalError()` might be an even better choice, compare http://stackoverflow.com/questions/29149040/ios8-swift-uicollectionreusableview-missing-return-in-a-function. — Martin R, May 17 '17 at 08:45
Actually the `default` case is not needed at all in Swift because the switch is exhaustive. Don't you get a *will never be executed* warning? — vadian, May 17 '17 at 08:46
@MartinR, I don't get will never be executed warning? so should I make it false ? — Steven, May 17 '17 at 08:56

score 0 · Accepted Answer · answered May 17 '17 at 08:53

0

Beacuse OC weak typing language, it can auto translate 0 to false, so in assert, it can be run, but swift is strong typing language, so you should use assert(false) or you should translate it by yourself

answered May 17 '17 at 08:53

Magic

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in swift assert(0) Cannot convert value of type Int to expected argument type Bool

1 Answers1