I have this enum with String values, which will be used to tell an API method that logs to a server what kind of serverity a message has. I'm using Swift 1.2, so enums can be mapped to Objective-C
#objc enum LogSeverity : String {
case Debug = "DEBUG"
case Info = "INFO"
case Warn = "WARN"
case Error = "ERROR"
}
I get the error
#objc enum raw type String is not an integer type
I haven't managed to find anywhere which says that only integers can be translated to Objective-C from Swift. Is this the case? If so, does anyone have any best-practice suggestion on how to make something like this available in Objective-C?
One of the solutions is to use the RawRepresentable protocol.
It's not ideal to have to write the init and rawValue methods but that allows you to use this enum as usual in both Swift and Objective-C.
#objc public enum LogSeverity: Int, RawRepresentable {
case debug
case info
case warn
case error
public typealias RawValue = String
public var rawValue: RawValue {
switch self {
case .debug:
return "DEBUG"
case .info:
return "INFO"
case .warn:
return "WARN"
case .error:
return "ERROR"
}
}
public init?(rawValue: RawValue) {
switch rawValue {
case "DEBUG":
self = .debug
case "INFO":
self = .info
case "WARN":
self = .warn
case "ERROR":
self = .error
default:
return nil
}
}
}
From the Xcode 6.3 release notes (emphasis added):
Swift Language Enhancements
...
Swift enums can now be exported to Objective-C using the #objc
attribute. #objc enums must declare an integer raw type, and cannot be
generic or use associated values. Because Objective-C enums are not
namespaced, enum cases are imported into Objective-C as the
concatenation of the enum name and case name.
Here's a solution that works.
#objc public enum ConnectivityStatus: Int {
case Wifi
case Mobile
case Ethernet
case Off
func name() -> String {
switch self {
case .Wifi: return "wifi"
case .Mobile: return "mobile"
case .Ethernet: return "ethernet"
case .Off: return "off"
}
}
}
Here is work around if you really want to achieve the goal. However, you can access the enum values in objects that Objective C accepts, not as actual enum values.
enum LogSeverity : String {
case Debug = "DEBUG"
case Info = "INFO"
case Warn = "WARN"
case Error = "ERROR"
private func string() -> String {
return self.rawValue
}
}
#objc
class LogSeverityBridge: NSObject {
class func Debug() -> NSString {
return LogSeverity.Debug.string()
}
class func Info() -> NSString {
return LogSeverity.Info.string()
}
class func Warn() -> NSString {
return LogSeverity.Warn.string()
}
class func Error() -> NSString {
return LogSeverity.Error.string()
}
}
To call :
NSString *debugRawValue = [LogSeverityBridge Debug]
If you don't mind to define the values in (Objective) C, you can use the NS_TYPED_ENUM macro to import constants in Swift.
For example:
.h file
typedef NSString *const ProgrammingLanguage NS_TYPED_ENUM;
FOUNDATION_EXPORT ProgrammingLanguage ProgrammingLanguageSwift;
FOUNDATION_EXPORT ProgrammingLanguage ProgrammingLanguageObjectiveC;
.m file
ProgrammingLanguage ProgrammingLanguageSwift = #"Swift";
ProgrammingLanguage ProgrammingLanguageObjectiveC = #"ObjectiveC";
In Swift, this is imported as a struct as such:
struct ProgrammingLanguage: RawRepresentable, Equatable, Hashable {
typealias RawValue = String
init(rawValue: RawValue)
var rawValue: RawValue { get }
static var swift: ProgrammingLanguage { get }
static var objectiveC: ProgrammingLanguage { get }
}
Although the type is not bridged as an enum, it feels very similar to one when using it in Swift code.
You can read more about this technique in Grouping Related Objective-C Constants
Code for Xcode 8, using the fact that Int works but other methods aren't exposed to Objective-C. This is pretty horrible as it stands...
class EnumSupport : NSObject {
class func textFor(logSeverity severity: LogSeverity) -> String {
return severity.text()
}
}
#objc public enum LogSeverity: Int {
case Debug
case Info
case Warn
case Error
func text() -> String {
switch self {
case .Debug: return "debug"
case .Info: return "info"
case .Warn: return "warn"
case .Error: return "error"
}
}
}
This is my use case:
I avoid hard-coded Strings whenever I can, so that I get compile warnings when I change something
I have a fixed list of String values coming from a back end, which can also be nil
Here's my solution that involves no hard-coded Strings at all, supports missing values, and can be used elegantly in both Swift and Obj-C:
#objc enum InventoryItemType: Int {
private enum StringInventoryItemType: String {
case vial
case syringe
case crystalloid
case bloodProduct
case supplies
}
case vial
case syringe
case crystalloid
case bloodProduct
case supplies
case unknown
static func fromString(_ string: String?) -> InventoryItemType {
guard let string = string else {
return .unknown
}
guard let stringType = StringInventoryItemType(rawValue: string) else {
return .unknown
}
switch stringType {
case .vial:
return .vial
case .syringe:
return .syringe
case .crystalloid:
return .crystalloid
case .bloodProduct:
return .bloodProduct
case .supplies:
return .supplies
}
}
var stringValue: String? {
switch self {
case .vial:
return StringInventoryItemType.vial.rawValue
case .syringe:
return StringInventoryItemType.syringe.rawValue
case .crystalloid:
return StringInventoryItemType.crystalloid.rawValue
case .bloodProduct:
return StringInventoryItemType.bloodProduct.rawValue
case .supplies:
return StringInventoryItemType.supplies.rawValue
case .unknown:
return nil
}
}
}
Here's what I came up with. In my case, this enum was in the context providing info for a specific class, ServiceProvider.
class ServiceProvider {
#objc enum FieldName : Int {
case CITY
case LATITUDE
case LONGITUDE
case NAME
case GRADE
case POSTAL_CODE
case STATE
case REVIEW_COUNT
case COORDINATES
var string: String {
return ServiceProvider.FieldNameToString(self)
}
}
class func FieldNameToString(fieldName:FieldName) -> String {
switch fieldName {
case .CITY: return "city"
case .LATITUDE: return "latitude"
case .LONGITUDE: return "longitude"
case .NAME: return "name"
case .GRADE: return "overallGrade"
case .POSTAL_CODE: return "postalCode"
case .STATE: return "state"
case .REVIEW_COUNT: return "reviewCount"
case .COORDINATES: return "coordinates"
}
}
}
From Swift, you can use .string on an enum (similar to .rawValue).
From Objective-C, you can use [ServiceProvider FieldNameToString:enumValue];
You can create an private Inner enum. The implementation is a bit repeatable, but clear and easy. 1 line rawValue, 2 lines init, which always look the same. The Inner has a method returning the "outer" equivalent, and vice-versa.
Has the added benefit that you can directly map the enum case to a String, unlike other answers here.
Please feel welcome to build on this answer if you know how to solve the repeatability problem with templates, I don't have time to mingle with it right now.
#objc enum MyEnum: NSInteger, RawRepresentable, Equatable {
case
option1,
option2,
option3
// MARK: RawRepresentable
var rawValue: String {
return toInner().rawValue
}
init?(rawValue: String) {
guard let value = Inner(rawValue: rawValue)?.toOuter() else { return nil }
self = value
}
// MARK: Obj-C support
private func toInner() -> Inner {
switch self {
case .option1: return .option1
case .option3: return .option3
case .option2: return .option2
}
}
private enum Inner: String {
case
option1 = "option_1",
option2 = "option_2",
option3 = "option_3"
func toOuter() -> MyEnum {
switch self {
case .option1: return .option1
case .option3: return .option3
case .option2: return .option2
}
}
}
}
I think #Remi 's answer crashes in some situations as I had this:
My error's screesshot. so I post my edition for #Remi 's answer:
#objc public enum LogSeverity: Int, RawRepresentable {
case debug
case info
case warn
case error
public typealias RawValue = String
public var rawValue: RawValue {
switch self {
case .debug:
return "DEBUG"
case .info:
return "INFO"
case .warn:
return "WARN"
case .error:
return "ERROR"
}
}
public init?(rawValue: RawValue) {
switch rawValue {
case "DEBUG":
self = .debug
case "INFO":
self = .info
case "WARN":
self = .warn
case "ERROR":
self = .error
default:
return nil
}
}
}
Related
I have enum in swift
enum Type {
case bool(Bool)
case int(Int)
case array([String])
}
Dont understand how i can convert this to kotlin code, i did like this:
enum class AnswerSheetType {
BOOL,
INT,
ARRAY
}
But how i can pass variable to enum type. For example then i want create method which will be return type with variable, like this(swift code):
func marks(for id: String) -> Type {
let answer = answers?[id]
if let boolAnswer = answer as? Bool {
return .bool(boolAnswer)
}
if let intAnswer = answer as? Int {
return .int(intAnswer)
}
if let arrayAnswer = answer as? [String] {
return .array(arrayAnswer)
}
}
You can use a sealed interface/class to represent this.
sealed interface Type {
data class BoolType(val value: Bool) : Type
data class IntType(val value: Int) : Type
data class ArrayType(val value: Array<String>) : Type
// if you have a case that doesn't have any associated values, just use an object
// object CaseWithoutAssociatedValues: Type
}
Usage:
// let someType: Type = .bool(true)
val someType: Type = Type.BoolType(true)
// just like how you can use a switch on a Swift enum, you can use a when like this too:
// This when is also exhaustive, if you specify all the implementers of Type
when (someType) {
is Type.BoolType -> println("Bool value: ${someType.value}")
is Type.IntType -> println("Int value: ${someType.value}")
is Type.ArrayType -> println("Array value: ${someType.value}")
}
Notice that in each of the branches, you can access someType.value, because of the smart-cast. This is unlike in Swift, where you would do pattern matching to get the associated values out.
As I was writing my answer Sweeper already answered with almost the identical solution. I wanted to add to that, that your marks function could then be written as this:
fun marks(id: String) : Type? {
when (val answer = answers?.get(id)) {
is Boolean -> return Type.BoolType(answer)
is Int -> return Type.IntType(answer)
is Array<*> -> if (answer.isArrayOf<String>()) return Type.ArrayType(answer as Array<String>)
}
return null
}
The Array case is a bit ugly but that is because checking on is Array<String> is not possible. The IDE will also still complain about having an unchecked cast but it should work. I don't know if there's a nicer way to handle this.
I have this enum in swift
#objc(PaymentMethods)
public enum PaymentMethods: Int, RawRepresentable {
public typealias RawValue = String
case card
case account
case paypal
public var rawValue: RawValue {
switch self {
case .card:
return "CARD"
case .account:
return "ACCOUNT"
case .paypal:
return "PAYPAL"
}
}
public init(rawValue: RawValue){
switch rawValue {
case "CARD":
self = .card
case "ACCOUNT":
self = .account
case "PAYPAL":
self = .paypal
default:
self = .card
}
}
}
And this property in a class.
#objc public class SomeClass: ExtendingSomeOtherStuffs {
var supportedPaymentMethods:[PaymentMethods]!
}
my problem is how to bridge supportedPaymentMethods into Objective-C and use it.
I have looked at this post and this but still can't figure it out.
can someone help me out with an example at least.
Am trying to use this in Native-script and I need to expose that property from Swift to Objective
You can do it like so:
#objc public class SomeClass: NSObject {
var supportedPaymentMethods: [PaymentMethods]
#objc init(supportedPaymentMethods: [String]) {
self.supportedPaymentMethods = supportedPaymentMethods.map { .init(rawValue: $0) }
}
}
and use it like this in your Objective-C code:
[[SomeClass alloc] initWithSupportedPaymentMethods:#[#"ACCOUNT", #"CARD", #"PAYPAL"]];
If you don't want your class initializer to take any String I would suggest doing the following:
Make your init(rawValue:) failable and return nil when the argument is invalid:
public init?(rawValue: RawValue) {
switch rawValue {
case "CARD":
self = .card
case "ACCOUNT":
self = .account
case "PAYPAL":
self = .paypal
default:
return nil
}
}
Use compactMap instead of map in the init of the SomeClass like so:
#objc init(supportedPaymentMethods: [String]) {
self.supportedPaymentMethods = supportedPaymentMethods.compactMap { .init(rawValue: $0) }
}
(it will eliminate the nil values)
I have a mixed project and came across an interesting issue.
There's an enum, defined in obj-c
typedef NS_ENUM (NSUInteger, ABCCategory) {
ABCCategoryFirst,
ABCCategorySecond
};
Next, there's a swift file where an extension is defined
extension ABCCategory: RawRepresentable {
public typealias RawValue = String
public init(rawValue: RawValue) {
switch rawValue {
case "first":
self = .first
case "second":
self = .second
default:
self = .first
}
}
public var rawValue: RawValue {
get {
switch self {
case .first:
return "first"
case .second:
return "second"
}
}
}
}
Everything works fine in the Debug configuration, but when I switch to Release it does not build, saying: Invalid redeclaration of 'rawValue'
I've tried removing typealias, replacing RawValue with String (so the protocol could implicitly guess the value), making constructor optional as in the protocol (and implicitly unwrapped optional also) - no go.
I do understand that extending an Int enum with string is a bit weird, but why it stops building in Release and working absolutely perfect in Debug?
Is there some different mechanism of treating enums/classes/extensions for Release configuration?
The raw value syntax for enums in Swift is “just” a shorthand for conformance to the RawRepresentable protocol. It’s easy to add this manually if you want to use otherwise unsupported types as raw values.
Source
I'm not sure why it works in debug because when you create a typed enum you are already 'conforming' to RawRepresentable. So when you create an NS_ENUM it is imported in to swift like so:
public enum ABCCategory : UInt {
case first
case second
}
Meaning that it already conforms to RawRepresentable. The fix can be achieved two ways, one in Swift and in Objective-C
In Swift we just remove the RawRepresentable and change rawValue to stringValue, and RawValue to String:
extension ABCCategory {
var stringValue: String {
switch self {
case .first: return "first"
case .second: return "second"
}
}
init(_ value: String) {
switch value {
case "first":
self = .first
case "second":
self = .second
default:
self = .first
}
}
}
Or you could just change the Objective-C to use NS_TYPED_ENUM. Some info here. However this will change your enum to a struct
.h
typedef NSString *ABCCategory NS_TYPED_ENUM;
extern ABCCategory const ABCCategoryFirst;
extern ABCCategory const ABCCategorySecond;
.m
ABCCategory const ABCCategoryFirst = #"first";
ABCCategory const ABCCategorySecond = #"second";
This will be imported by swift like so:
public struct ABCCategory : Hashable, Equatable, RawRepresentable {
public init(rawValue: String)
}
public static let first: ABCCategory
public static let second: ABCCategory
We know how to expose Swift enums to Obj-C:
#objc enum Animal: Int {
case Cat, Dog
}
But the compiler complains that the following "cannot be represented in Obj-C":
func myAnimal() -> Animal? {
if hasPet() {
return .Cat
} else {
return nil
}
}
Ideas?
Optional Ints in Swift don't map to a type in Objective-C. The issue is that your myAnimal() method is returning a type that can't be represented in Objective-C.
The way I see it, you have two options...
Option1: Change your method's return type:
func myAnimal() -> NSNumber? {
// method body goes here.
}
This doesn't really seem great since in Objective-C you'd have to do something like this:
if (myAnimal().integerValue == AnimalCat) {
// do stuff here
}
Option 2: Add a catch-all case in your enum
#objc enum Animal: Int {
case none = 0
case cat = 1
case dog = 2
init(rawValue: Int) {
switch rawValue {
case 1: self = Cat
case 2: self = Dog
default: self = None
}
}
}
// Updated method signature that makes the compiler happy.
func myAnimal() -> Animal {
if hasPet() {
return .Cat
} else {
return .None
}
}
This way, you can change your method signature to not return an optional, and the compiler will be happy.
Is there a way to use new Swift3 enums with associated value in Objective-C?
Is there a way to declare/bridge Swift3 enums with associated value in Objective-C, if I develop a library and want to give Swift3 users convenient API?
I'm afraid it's not possible, Apple has a list of Swift Type Compatibility which explicitly excludes enumerations defined in Swift without Int raw value type.
Reference
This is what I did:
In Swift class created the enum
enum Origin {
case Search(searchTerm: String, searchResultsPageNum: Int)
case Discovery(pageNum: Int)
}
Then in my Class, created enum property and functions (that are visible to Objective C) to set and get values of the enum property.
#objc class GameSession: NSObject
{
...
var gameOrigin: Origin?
...
let originStr = "origin"
let notSpecified = "Not Specified"
#objc func getOrigin() -> NSDictionary
{
guard let origin = gameOrigin else {
return [originStr: notSpecified]
}
switch origin {
case .Search(let searchTerm, let searchResultsPageNum):
return ["searchTerm": searchTerm, "searchResultsPageNum": "\(searchResultsPageNum)"]
case .Discovery(let pageNum)
return ["pageNum": pageNum]
default:
return [originStr: notSpecified]
}
}
#objc func setSearchOriginWith(searchTerm: String, searchResultsPageNum: Int, filtered:Bool)
{
self.gameOrigin = Origin.Search(searchTerm: searchTerm, searchResultsPageNum: searchResultsPageNum, filtered: filtered)
}
#objc func setDiscoveryOriginWith(pageNum: Int)
{
self.gameOrigin = Origin.Discovery(pageNum: pageNum)
}
}