A little type-safe CKRecord extension to prevent typo.

CKRecord+RawRepresentable.swift

extension CKRecord {
    subscript<T: RawRepresentable>(key: T) -> CKRecordValueProtocol? where T.RawValue == CKRecord.FieldKey {
        get {
            return self[key.rawValue]
        }
        set {
            self[key.rawValue] = newValue
        }
    }
}

Usage.swift

enum Key: CKRecord.FieldKey {
    case aaa
    case bbb
}

func usage() {
    let record = CKRecord(recordType: "Test")
    record[Key.aaa] = true

    let value = record[Key.aaa]
    // type of `value` is `CKRecordValueProtocol?`
    
    print(value)
    // Optional(1)
}

Similar to CKRecord's default subscript access, getting a value requires a typecast.