Stack overflow when defining subscript on CKRecord in Swift

Question

This question asks whether one can use subscripting with CKRecord in Swift. While I already knew how to do what the questioner wanted, every permutation of it g

Answer 1

I was able to successfully subscript by piggy-backing off of some code written by an Apple engineer on dev forums.

import CloudKit

protocol MyCKRecordValueType {
    var asObject: CKRecordValue { get }
}

extension CKRecord {
    func set(value: ValueType, forKey key: String) where ValueType : MyCKRecordValueType {
        let object = value.asObject
        self.setObject(object, forKey: key)
    }
    subscript(key : String) -> MyCKRecordValueType? {
        set {
            self.setObject(newValue?.asObject, forKey: key)
        }
        get {
            return object(forKey: key) as? MyCKRecordValueType
        }
    }
}

extension String : MyCKRecordValueType {
    var asObject: CKRecordValue { return self as NSString }
}
extension Bool : MyCKRecordValueType {
    var asObject: CKRecordValue { return self as NSNumber }
}
extension Int : MyCKRecordValueType {
    var asObject: CKRecordValue { return self as NSNumber }
}
extension Data : MyCKRecordValueType {
    var asObject: CKRecordValue { return self as NSData }
}

you can then call the subscript as you would expect:

let firstRecordID = CKRecordID(recordName: "0")

        let record = CKRecord(recordType: "Foo", recordID: firstRecordID)

        record["title"] = "Hello World"

        record["year_established"] = 2000