CODEWITHSUNDEEP
swiftdebuggingerror-handling
Kurt Peek
Kurt Peek

Reputation: 57511

In Swift debugger, how can I see where an exception is caught?

I'm working with a Swift model Cardholder which is initialized based on an API response, and I'm trying to figure out what happens if certain fields in the response are null. Here is a (simplified) extension of the Cardholder model with an initializer from a Decoder:

extension Cardholder: DictionaryDeserializable, DictionarySerializable {
    private enum CodingKeys: String, CodingKey {
        case id = "id"
        case firstName = "first_name"
        case lastName = "last_name"
        case dateOfBirth = "date_of_birth"
    }

    public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        id = try container.decode(String.self, forKey: .id)
        firstName = try container.decode(String.self, forKey: .firstName)
        lastName = try container.decode(String.self, forKey: .lastName)
        dateOfBirth = try container.decode(Date.self, forKey: .dateOfBirth)
    }
}

For the API response that I'm manually testing with, the first_name field is null, and what I'm finding is that the debugger steps straight to the end of the init method after the firstName = line:

Xcode debugger with current line of execution at end of init

This happens if I press the 'Step Over' or 'Step In' buttons.

From what I understand rom https://docs.swift.org/swift-book/LanguageGuide/ErrorHandling.html, this init method is a throwing function which propagates errors that are thrown inside of it to the scope from which it’s called. How would I get to that scope to figure out what the ultimate consequences are of this error?

Upvotes: 1

Views: 73

Answers (1)

Rob Napier
Rob Napier

Reputation: 299345

Throwing an error in Swift is not an exception. It's just a fancy kind of return. You can step up the calling stack just like you would for return. Step-out; it's the button to the right of step-into.

Upvotes: 3

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