setValueForKeys失败了Swift

Question

I have the following code in the Playground:

class Pokemon : NSObject {

    var name :String!
    var id :Int?
    var imageURL :String!
    var latitude :Double!
    var longitude :Double!

    init(dictionary :[String:Any]) {

        super.init()
        setValuesForKeys(dictionary)
}
}

let dict :[String:Any] = ["name":"John","imageURL":"someimageURL","latitude":45.67]
let pokemon = Pokemon(dictionary: dict)

When the call to setValuesForKeys is made then it throws an exception saying the following:

*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<__lldb_expr_13.Pokemon 0x6000000ffd00> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key latitude.'

I have the key "latitude" but for some reason it is not able to find it. Any ideas!

Answer 1

The type Double! (similarly Double? ) has no correspondence in the Objective-C world, so it is not exposed as an Objective-C property , so Key-Value Coding cannot find a key named "latitude" and crash.

You should convert those fields to non-optional if you need KVC.

class Pokemon : NSObject {
    var name: String!
    var id: Int = 0
    var imageURL: String!
    var latitude: Double = 0.0
    var longitude: Double = 0.0

    init(dictionary: [String: Any]) {
        super.init()
        setValuesForKeys(dictionary)
    }
}