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swift5property-wrapper

Property Wrapped Value if accessed from other files give non optional type


struct HarkAppPreference {

    @UserPreferenceField(key: .userSelectedTags)
    static var userSelectedTags: [MLQTag]

    @UserPreferenceField(key: .userLastActivePlalist)
    static var userLastActivePlaylist: [PlayableEntity]

    @UserPreferenceField(key: .userLastActivePlayableEntityMeta)
    static var userLastActivePlayableEntityMeta: LastPlayableEntityMeta

    @UserPreferenceField(key: .currentUSer)
    static var user: User

}

enum UserPreferenceFieldKey : String {

    case userSelectedTags = "MLQUserSelectedTags"
    case userLastActivePlalist = "MLQUserLastActivePlalist"
    case userLastActivePlayableEntityMeta = "MLQUserLastActivePlayableEntityMeta"
    case currentUSer

}

struct User : Codable {
    let name : String
    let phone: String
}

@propertyWrapper
struct UserPreferenceField<T : Codable> {
    let key: UserPreferenceFieldKey
    var wrappedValue : T? {
        get {
            guard let decodedData = UserDefaults.standard.value(forKey: key.rawValue) as? Data else { return nil }
            return try? JSONDecoder().decode(T.self, from: decodedData)

        }
        set {
            do {
                let encodedValue = try JSONEncoder().encode(newValue)
                 UserDefaults.standard.set(encodedValue, forKey: key.rawValue)
            } catch {
                 print("Error in saving codable value - \(error.localizedDescription)")
            }
        }
    }

    init(key:UserPreferenceFieldKey) {
        self.key = key

    }
}

This is my PropertyWrapper which I created to use for saving data to UserDefault, this worked to my expectations to use the value with optional chaining if used from within the file where I have written the PropertyWrapper code.

But this given an error Initializer for conditional binding must have Optional type, not 'User' when used in another file like below

class ABC {

    func sss(){
        if let _ = HarkAppPreference.user { // here is gives error

        }
    }

}

But if the same is used in the same file it works fine with optional chaining.


Solution

  • As per the reply from Apple Developers Team on Dev forum, It's not happening in Xcode 11.3 and worked fine when added optional to declared property.