My Object conforms to the new Swift 4 Codeable protocol. How to save an array of these Objects in UserDefaults?
struct MyObject: Codeable {
var name: String
var something: [String]
}
myObjectsArray = [MyObject]() // filled with objects
UserDefaults.standard.set(myObjectsArray, forKey: "user_filters")
Error
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Attempt to insert non-property list object
Whew, I got it working:
Here is the Swift 4 Syntax to save an Array with Codeable Objects:
My solution is to encode it as a JSON Object and save that:
static var getAllObjects: [MyObject] {
let defaultObject = MyObject(name: "My Object Name")
if let objects = UserDefaults.standard.value(forKey: "user_objects") as? Data {
let decoder = JSONDecoder()
if let objectsDecoded = try? decoder.decode(Array.self, from: objects) as [MyObject] {
return objectsDecoded
} else {
return [defaultObject]
}
} else {
return [defaultObject]
}
}
static func saveAllObjects(allObjects: [MyObject]) {
let encoder = JSONEncoder()
if let encoded = try? encoder.encode(allObjects){
UserDefaults.standard.set(encoded, forKey: "user_objects")
}
}
You can use a more generic approach, using array with specific type:
(myObject = any custom codable object you like)
(myKey = a string constant key to be able to retrieve/set specific array)
//set
setObject(myArray, forKey: mykey)
//get
let myArray = getObject(forKey: mykey, castTo: Array<myObject>.self)
and generic functions also, for any type:
func setObject<Object>(_ object: Object, forKey: String) where Object: Encodable
{
let encoder = JSONEncoder()
do {
let data = try encoder.encode(object)
set(data, forKey: forKey)
synchronize()
} catch let encodeErr {
print("Failed to encode object:", encodeErr)
}
}
func getObject<Object>(forKey: String, castTo type: Object.Type) -> Object? where Object: Decodable
{
guard let data = data(forKey: forKey) else { return nil }
let decoder = JSONDecoder()
do {
let object = try decoder.decode(type, from: data)
return object
} catch let decodeError{
print("Failed to decode object:" , decodeError)
return nil
}
}
