Computed variable setter inside another computed variable setter crashes the app - ios

Question

This code leads to crash somewhere later with EXC_BAD_ACCESS
SomeLoader().selectedIndex = 1
class SomeLoader {
// MARK: - Public
var selectedIndex: Int? {
get {
return dataStorage.selectedIndex
}
set {
dataStorage.selectedIndex = newValue
}
}
}
this code is not crashed:
SomeLoader().selectedIndex = 1
class SomeLoader {
// MARK: - Public
var selectedIndex: Int? {
get {
return dataStorage.selectedIndex
}
set {
dataStorage.updateSelected(index: newValue)
}
}
}
where:
struct DataStorage<T: Hashable> {
enum Keys: String {
case selectedIndex
}
private func get<U>(forKey key: String) -> U? {
guard let objectData = getData(forKey: key) else {
return nil
}
let object: U? = get(forData: objectData)
return object
}
private func get<U>(forData objectData: Data) -> U? {
return NSKeyedUnarchiver.unarchiveObject(with: objectData) as? U
}
private func save<U>(forKey key: String, object: U) {
let encodedData = NSKeyedArchiver.archivedData(withRootObject: object)
UserDefaults.standard.set(encodedData, forKey: key)
}
}
extension DataStorage {
func updateSelected(index: Int?) {
guard let index = index else {
remove(forKey: Keys.selectedIndex.rawValue)
return
}
saveSelected(index: index)
}
var selectedIndex: Int? {
get {
return get(forKey: Keys.selectedIndex.rawValue)
}
set {
guard let index = newValue else {
remove(forKey: Keys.selectedIndex.rawValue)
return
}
saveSelected(index: index)
}
}
}
Why? Is it a bug?
Screenshots with an error and a callstack. The error appears later in the other part of the code.
The code below crashes in the iOS. But works in the playground.
//: Playground - noun: a place where people can play
import UIKit
struct DataStorage<T: Hashable> {
enum Keys: String {
case selectedIndex
}
private func get<U>(forKey key: String) -> U? {
guard let objectData = getData(forKey: key) else {
return nil
}
let object: U? = get(forData: objectData)
return object
}
private func get<U>(forData objectData: Data) -> U? {
return NSKeyedUnarchiver.unarchiveObject(with: objectData) as? U
}
private func save<U>(forKey key: String, object: U) {
let encodedData = NSKeyedArchiver.archivedData(withRootObject: object)
UserDefaults.standard.set(encodedData, forKey: key)
}
private func remove(forKey key: String) {
UserDefaults.standard.removeObject(forKey: key)
}
private func saveSelected(index: Int) {
save(forKey: Keys.selectedIndex.rawValue, object: index)
}
private func getData(forKey key: String) -> Data? {
return getContent(forKey: key) as? Data
}
private func getContent(forKey key: String) -> Any? {
return UserDefaults.standard.value(forKey: key)
}
}
extension DataStorage {
func updateSelected(index: Int?) {
guard let index = index else {
remove(forKey: Keys.selectedIndex.rawValue)
return
}
saveSelected(index: index)
}
var selectedIndex: Int? {
get {
return get(forKey: Keys.selectedIndex.rawValue)
}
set {
guard let index = newValue else {
remove(forKey: Keys.selectedIndex.rawValue)
return
}
saveSelected(index: index)
}
}
}
class SomeLoader {
// MARK: - Public
var dataStorage = DataStorage<Int>()
var selectedIndex: Int? {
get {
return dataStorage.selectedIndex
}
set {
dataStorage.selectedIndex = newValue
}
}
}
let someLoader = SomeLoader()
someLoader.selectedIndex = 1
print(someLoader)
The code below works everywhere
//: Playground - noun: a place where people can play
import UIKit
struct DataStorage<T: Hashable> {
enum Keys: String {
case selectedIndex
}
private func get<U>(forKey key: String) -> U? {
guard let objectData = getData(forKey: key) else {
return nil
}
let object: U? = get(forData: objectData)
return object
}
private func get<U>(forData objectData: Data) -> U? {
return NSKeyedUnarchiver.unarchiveObject(with: objectData) as? U
}
private func save<U>(forKey key: String, object: U) {
let encodedData = NSKeyedArchiver.archivedData(withRootObject: object)
UserDefaults.standard.set(encodedData, forKey: key)
}
private func remove(forKey key: String) {
UserDefaults.standard.removeObject(forKey: key)
}
private func saveSelected(index: Int) {
save(forKey: Keys.selectedIndex.rawValue, object: index)
}
private func getData(forKey key: String) -> Data? {
return getContent(forKey: key) as? Data
}
private func getContent(forKey key: String) -> Any? {
return UserDefaults.standard.value(forKey: key)
}
}
extension DataStorage {
func updateSelected(index: Int?) {
guard let index = index else {
remove(forKey: Keys.selectedIndex.rawValue)
return
}
saveSelected(index: index)
}
var selectedIndex: Int? {
get {
return get(forKey: Keys.selectedIndex.rawValue)
}
set {
guard let index = newValue else {
remove(forKey: Keys.selectedIndex.rawValue)
return
}
saveSelected(index: index)
}
}
}
class SomeLoader {
// MARK: - Public
var dataStorage = DataStorage<Int>()
var selectedIndex: Int? {
get {
return dataStorage.selectedIndex
}
set {
dataStorage.updateSelected(index: newValue)
}
}
}
let someLoader = SomeLoader()
someLoader.selectedIndex = 1
print(someLoader)