Enum of structs in Swift 3.0 - ios

I am trying to create an enum of a struct that I would like to initialize:
struct CustomStruct {
var variable1: String
var variable2: AnyClass
var variable3: Int
init (variable1: String, variable2: AnyClass, variable3: Int) {
self.variable1 = variable1
self.variable2 = variable2
self.variable3 = variable3
}
}
enum AllStructs: CustomStruct {
case getData
case addNewData
func getAPI() -> CustomStruct {
switch self {
case getData:
return CustomStruct(variable1:"data1", variable2: SomeObject.class, variable3: POST)
case addNewData:
// Same to same
default:
return nil
}
}
}
I get the following errors:
Type AllStructs does not conform to protocol 'RawRepresentable'
I am assuming that enums cannot be used this way. We must use primitives.

It should be:
struct CustomStruct {
var apiUrl: String
var responseType: AnyObject
var httpType: Int
init (variable1: String, variable2: AnyObject, variable3: Int) {
self.apiUrl = variable1
self.responseType = variable2
self.httpType = variable3
}
}
enum MyEnum {
case getData
case addNewData
func getAPI() -> CustomStruct {
switch self {
case .getData:
return CustomStruct(variable1: "URL_TO_GET_DATA", variable2: 11 as AnyObject, variable3: 101)
case .addNewData:
return CustomStruct(variable1: "URL_TO_ADD_NEW_DATA", variable2: 12 as AnyObject, variable3: 102)
}
}
}
Usage:
let data = MyEnum.getData
let myObject = data.getAPI()
// this should logs: "URL_TO_GET_DATA 11 101"
print(myObject.apiUrl, myObject.responseType, myObject.httpType)
Note that upon Naming Conventions, struct should named as CustomStruct and enum named as MyEnum.
In fact, I'm not pretty sure of the need of letting CustomStruct to be the parent of MyEnum to achieve what are you trying to; As mentioned above in the snippets, you can return an instance of the struct based on what is the value of the referred enum.

I'm not commenting on the choice to use an enum here, but just explaining why you got that error and how to declare an enum that has a custom object as parent.
The error shows you the problem, CustomStruct must implement RawRepresentable to be used as base class of that enum.
Here is a simplified example that shows you what you need to do:
struct CustomStruct : ExpressibleByIntegerLiteral, Equatable {
var rawValue: Int = 0
init(integerLiteral value: Int){
self.rawValue = value
}
static func == (lhs: CustomStruct, rhs: CustomStruct) -> Bool {
return
lhs.rawValue == rhs.rawValue
}
}
enum AllStructs: CustomStruct {
case ONE = 1
case TWO = 2
}
A few important things that we can see in this snippet:
The cases like ONE and TWO must be representable with a Swift literal, check this Swift 2 post for a list of available literals (int,string,array,dictionary,etc...). But please note that in Swift 3, the LiteralConvertible protocols are now called ExpressibleByXLiteral after the Big Swift Rename.
The requirement to implement RawRepresentable is covered implementing one of the Expressible protocols (init?(rawValue:) will leverage the initializer we wrote to support literals).
Enums must also be Equatable , so you'll have to implement the equality operator for your CustomStruct base type.

Did you try conforming to RawRepresentable like the error is asking?
Using JSON representation should work for variable1 and variable3. Some extra work may be required for variable2.
struct CustomStruct: RawRepresentable {
var variable1: String
var variable2: AnyClass
var variable3: Int
init?(rawValue: String) {
guard let data = rawValue.data(using: .utf8) else {
return nil
}
guard let json = try? JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] else {
return nil
}
self.variable1 = (json["variable1"] as? String) ?? ""
self.variable2 = (json["variable2"] as? AnyClass) ?? AnyClass()
self.variable3 = (json["variable3"] as? Int) ?? 0
}
var rawValue: String {
let json = ["variable1": self.variable1,
"variable2": self.variable2,
"variable3": self.variable3
]
guard let data = try? JSONSerialization.data(withJSONObject: json, options: []) else {
return ""
}
return String(data: data, encoding: .utf8) ?? ""
}
}

According to the documentation:
If a value (known as a “raw” value) is provided for each enumeration case, the value can be a string, a character, or a value of any integer or floating-point type.
So yes, you cannot set a struct type to be enum's raw value.
In your case I would suggest using string as the enum raw value and some dictionary mapping these strings to CUSTOM_STRUCT type.

A bit late on the party but maybe useful for someone else. I would consider to simply use computed variables instead of a struct.
enum MyEnum {
case getData
case addNewData
var variable1: String {
switch self {
case .getData: return "data1"
case .addNewData: return "data2"
}
}
var variable2: Int {
switch self {
case .getData: return 1
case .addNewData: return 2
}
}
// ....
}
Usage:
let data = MyEnum.getData
print (data.variable1) // "data1"

Related

Dynamically access property of property of struct

I have a large numbers of structs and all of them have responseId: String and there is a property with same name as the value of responseId that contains contactId: String.
responseId is always non-optional String.
contactId of inner object is also non-optional String
all inner objects are optional (at runtime only one of the objects will be non-nil)
Below are two examples:
protocol ContainerBase {
var responseId: String { get }
}
struct Container1: ContainerBase {
struct OtherA {
let contactId: String
let cats: [String] // Other info here, not related to OtherB
}
struct OtherB {
let contactId: String
let dogsNum: Int // Other info here, not related to OtherA
}
let responseId: String
let otherA: OtherA? // Optional
let otherB: OtherB? // Optional
}
struct Container2: ContainerBase {
struct AnotherA {
let contactId: String
let passed: Bool // Other info here, not related to AnotherB
}
struct AnotherB {
let contactId: String
let friend: String // Other info here, not related to AnotherA
}
let responseId: String
let anotherA: AnotherA? // Optional
let anotherB: AnotherB? // Optional
}
Question:
How can I access contactId from Container1 or Container2 dynamically? (I tried the non dynamic approach with an extra function for each ContainerN struct with a switch inside but this is getting crazy because I have too many this structs, I already made some typos and forgot some cases, caused bugs,... and I imagine the reliable solution is "reflexion"?).
Example:
For example, if responseId of Container1 is "otherA" then I should look for contactId inside of property otherA. Since I have several types of Containers with different types of unrelated inner objects each one, solution should not be specific to Container1 nor Container2 it should work with any ContainerBase.
I implemented a dirty code but it causes a warning and cannot find to work it without generating one. Also I think this does not work reliably (This is for my iOS app but this strangely this does not work in linux Swift). Is this even possible? or it is a compiler glitch?
let c1 = Container1(
responseId: "otherA",
otherA: Container1.OtherA(contactId: "123", cats: ["figaro"]),
otherB: nil)
c1.findContactId() // expected "123"
Ugly code ahead:
extension ContainerBase {
func findContactId() -> String? {
let mirror = Mirror(reflecting: self)
guard let tInnerRes = mirror.children.first(where: { $0.label == self.responseId })?.value else { return nil }
// WARN: Conditional cast from 'Any' to 'Optional<Any>' always succeeds
guard let maybeInnerRes = (tInnerRes as? Optional<Any>) else { return nil }
guard let innerRes = maybeInnerRes else { return nil }
let innerMirror = Mirror(reflecting: innerRes)
let contactId = innerMirror.children.first(where: { $0.label == "contactId" })?.value as? String
return contactId
}
}
Any help is appreciated
I asked the same question (but better explained) in the swift forums and got a great answer from Alexis Schultz:
func findContactId() -> String? {
Mirror(reflecting: self)
.children
.first(where: { $0.label == responseId })
.map(\.value)
.flatMap(Mirror.init(reflecting:))?
.children
.first(where: { $0.label == "some" })
.map(\.value)
.flatMap(Mirror.init(reflecting:))?
.children
.first(where: { $0.label == "contactId" })?
.value as? String
}
Later, after seeing word "some" I realized that Mirror's descendant function can do exactly the same job:
func findContactId() -> String? {
let mirror = Mirror(reflecting: self)
let value = mirror.descendant(responseId, "some", "contactId") as? String
return value
}

Swift 5: saving complex objects to file storage

I am working on a school assignment for which I have to develop an iOS application in Swift 5. The application needs to utilize a web service (a web-API) and either file storage or user defaults.
I had chosen to develop a "QR code manager", in which users can create QR codes for a URL by setting a few design parameters, which are then sent to a generator API. This API (upon an OK request) returns an image in a specified format (PNG in my case).
I have a class with the URL and all the design properties of the QR code, which will also contain the image itself. Please see below code snippet for the class.
public class QRCode {
var bsId : Int?
var url : String?
var name: String?
var frame: Frame?
var logo: QrCodeLogo?
var marker: Marker?
var color : String?
var bgColor : String?
var image : Data?
init(data: [String:String]) {
self.url = data["url"]
self.frame = Frame.allCases.first(where: { $0.description == data["frame"] })
self.logo = QrCodeLogo.allCases.first(where: { $0.description == data["logo"] })
self.marker = Marker.allCases.first(where: { $0.description == data["marker"] })
self.bgColor = data["backGroundColor"]
self.color = data["colorLight"]
}
init(json: String) {
// todo
}
}
extension QRCode {
func toDict() -> [String:Any] {
var dict = [String:Any]();
let otherSelf = Mirror(reflecting: self);
for child in otherSelf.children {
if let key = child.label {
dict[key] = child.value;
}
}
return dict;
}
}
All the properties are nullable for ease of development, the class will be further refactored once I have successfully implemented everything.
I have tried various methods I found all over the internet, one of which can be found in the class extension. The function toDict() translates the object properties and their values to a Dictionary object of type [String:Any]. However, I read that when the Any datatype is encoded and then decoded, Swift cannot determine which complex datatype the decoded data is supposed to be, effectively rendering the data either meaningless or unusable.
Another method I found was through extending the Codable-protocol in the class. As far as I am aware however, Codable only accepts primitive datatypes.
Please find below my currently written code for file storage handling. It is not complete yet, but I felt it was a good start and might help in this question.
class StorageManager {
fileprivate let filemanager: FileManager = FileManager.default;
fileprivate func filePath(forKey key: String) -> URL? {
guard let docURL = filemanager.urls(for: .documentDirectory, in: FileManager.SearchPathDomainMask.userDomainMask).first else {
return nil;
}
return docURL.appendingPathComponent(key);
}
func writeToStorage(identifier: String, data: QRCode) -> Void {
guard let path = filePath(forKey: identifier) else {
throw ApplicationErrors.runtimeError("Something went wrong writing the file to storage");
}
let dict = data.toDict();
// TODO:: Implement
}
func readFromStorage(identifier: String) -> Any {
// TODO:: Implement
return 0;
}
func readAllFromStorage() throws -> [URL] {
let docsURL = filemanager.urls(for: .documentDirectory, in: .userDomainMask)[0];
do {
let fileURLs = try filemanager.contentsOfDirectory(at: docsURL, includingPropertiesForKeys: nil);
return fileURLs;
} catch {
throw ApplicationErrors.runtimeError("Something went wrong retrieving the files from \(docsURL.path): \(error.localizedDescription)");
}
}
}
I am very new to Swift and I am running stuck on file storage. Is there any way I could store instances of this class in file storage in such a way that I could reïnstantiate this class when I retrieve the data?
Thanks in advance! Please do not hesitate to ask any questions if there are any.
Edit
Based on matt's comment, please find below the code snippets of the Marker, Frame, and QrCodeLogo enums.
The Frame enum:
public enum Frame: String, CaseIterable {
case noFrame
case bottomFrame
case bottomTooltip
case topHeader
static var count: Int { return 4 }
var description: String {
switch self {
case .noFrame:
return "no-frame"
case .bottomFrame:
return "bottom-frame"
case .bottomTooltip:
return "bottom-tooltip"
case .topHeader:
return "top-header"
}
}
}
The QrCodeLogo enum:
public enum QrCodeLogo: String, CaseIterable {
case noLogo
case scanMe
case scanMeSquare
static var count: Int { return 3 }
var description: String {
switch self {
case .noLogo:
return "no-logo"
case .scanMe:
return "scan-me"
case .scanMeSquare:
return "scan-me-square"
}
}
}
The Marker enum:
public enum Marker: String, CaseIterable {
case version1
case version2
case version3
case version4
case version5
case version6
case version7
case version8
case version9
case version10
case version11
case version12
case version13
case version15
case version16
static var count: Int { return 15 }
var description: String {
switch self {
case .version1:
return "version1"
case .version2:
return "version2"
case .version3:
return "version3"
case .version4:
return "version4"
case .version5:
return "version5"
case .version6:
return "version6"
case .version7:
return "version7"
case .version8:
return "version8"
case .version9:
return "version9"
case .version10:
return "version10"
case .version11:
return "version11"
case .version12:
return "version12"
case .version13:
return "version13"
case .version15:
return "version15"
case .version16:
return "version16"
}
}
}
All the above enums contain the valid design options for the API I use. They serve as an input restriction to prevent "invalid parameter"-errors from occurring.
Hopefully, this clears things up.
Thanks again!
A type can conform to Codable provided all its properties conform to Codable. All of your properties do conform to Codable except for the enums, and they will conform to Codable if you declare that they do. Thus, this simple sketch of your types compiles:
public enum Frame: String, Codable {
case noFrame
case bottomFrame
case bottomTooltip
case topHeader
}
public enum QrCodeLogo: String, Codable {
case noLogo
case scanMe
case scanMeSquare
}
public enum Marker: String, Codable {
case version1
case version2
case version3
case version4
case version5
case version6
case version7
case version8
case version9
case version10
case version11
case version12
case version13
case version15
case version16
}
public class QRCode : Codable {
var bsId : Int?
var url : String?
var name: String?
var frame: Frame?
var logo: QrCodeLogo?
var marker: Marker?
var color : String?
var bgColor : String?
var image : Data?
}
There are many, many other things about your code that could be improved.
You don't need CaseIterable or description for anything. Now that your type is Codable, you can use it to retrieve the values from JSON directly, automatically. If the names of your enum cases do not match the corresponding JSON keys, just make a CodingKey nested enum to act as a bridge.
In other words, being Codable makes your type both populatable directly from the JSON and serializable to disk.

How I can get rawValue from enum, if element is Any?

I have a variable of type Any?. I'm totally know what that variable is type of enum: String. How I can get rawValue something like:
var somevar: Any? = someValue
(somevar as ?????).rawValue
First of all sorry I misunderstood your question.
Yes it is possible and very EASY
it is beauty of swift
You have to add some extra step there
Step1 :
Add protocol
protocol TestMe {
var rawValueDesc: String {get}
}
Step 2 :
In your enum implement it
enum YourEnum:String,TestMe {
case one = "test"
case two = "test1"
var rawValueDesc: String {
return self.rawValue
}
}
Finally
var testdd:Any = YourEnum.one
if let finalValue = testdd as? TestMe {
print( finalValue.rawValueDesc)
}
Hope it is helpful to you
Assuming you have this defined somewhere in your or in imported module:
enum First: String {
case a, b
}
enum Second: String {
case c, d
}
In you module your should do something like this:
protocol StringRawRepresentable {
var rawValue: String { get }
}
extension First: StringRawRepresentable {}
extension Second: StringRawRepresentable {}
And here's your problem:
var somevar: Any? = someValue
let result = (somevar as? StringRawRepresentable)?.rawValue
If, for example, someValue == Second.c you gonna get "c" in result.
This approach will work, but you will have to extend all the possible types, otherwise as? casting will result in nil even if type has rawValue: String property.

Serialize enum struct that have cases with arguments

I have an enum struct like that:
enum MyStruct {
case CanRegister(String, String)
case Register(String, String, String, String, String?)
case Login(String, String)
...
}
Is it possible to serialize / encode and decode struct like that so I can easily save states to NSUserDefaults?
I know how to serialize custom structs, even enums that are of type: enum MyStruct : String{}, but can I do that with that kind of structure and how?
Thanks
I assume that you want a general method here, rather than one hard-coded for your specific enum. I haven't worked it all the way through, but using Mirror is where you should start. Consider this as a hint rather than an answer...
(p.s. this is based on ideas from this article)
enum MyStruct {
case IntVal(Int)
case CanRegister(String, String)
case Register(String, String, String, String, String?)
case Login(String, String)
// ...
}
func prettyPrint(_ any: Any) -> String {
let m = Mirror(reflecting: any)
var a: String
switch m.displayStyle {
case .some(.tuple):
a = "Tuple"
case .some(.enum):
a = "Enum"
default:
return "\(m.displayStyle)"
}
a += " \(m.subjectType) = ("
for case let (label?, value) in m.children {
a += "\(label), \(value)"
}
return a + ")"
}
let ab = MyStruct.CanRegister("A", "B")
let i = MyStruct.IntVal(7)
prettyPrint(ab) // "Enum MyStruct = (CanRegister, ("A", "B"))"
prettyPrint(i) // "Enum MyStruct = (IntVal, 7)"

How to get a swift enum's associated value regardless of the enum case

I have an object FormField which has two properties: a String name, and a value which can accept any type--hence I've made it Any!. However, I've been told in a separate question to use an enum with associated values instead of Any!.
enum Value {
case Text(String!)
case CoreDataObject(NSManagedObject!)
}
class FormField {
var name: String
var value: Value?
// initializers...
}
This approach makes it awfully verbose to check for nullity however. If I wanted to display an alert view for all the missing fields in the form, I'll have to repeat a nil check for every case in a switch statement:
for field in self.fields {
if let value = field.value {
switch value {
case .Text(let text):
if text == nil {
missingFields.append(field.name)
}
case .CoreDataObject(let object):
if object == nil {
missingFields.append(field.name)
}
}
}
}
Is there a shorter way of accessing the enum's associated value, regardless of the type? If I make FormField.value an Any! the above code would be as easy as:
for field in self.fields {
if field.value == nil {
missingFields.append(field.name)
}
}
Define a method isMissing() inside the enum - write it once and only once. Then you get nearly exactly what you prefer:
for field in self.fields {
if field.value.isMissing() {
missingFields.append(field.name)
}
}
It would look something like this (from the Swift Interpreter):
1> class Foo {}
>
2> enum Value {
3. case One(Foo!)
4. case Two(Foo!)
5.
6. func isMissing () -> Bool {
7. switch self {
8. case let .One(foo): return foo == nil
9. case let .Two(foo): return foo == nil
10. }
11. }
12. }
13> let aVal = Value.One(nil)
aVal: Value = One {
One = nil
}
14> aVal.isMissing()
$R0: Bool = true
With Swift 2 it's possible to get the associated value using reflection.
To make that easier just add the code below to your project and extend your enum with the EVAssociated protocol.
public protocol EVAssociated {
}
public extension EVAssociated {
public var associated: (label:String, value: Any?) {
get {
let mirror = Mirror(reflecting: self)
if let associated = mirror.children.first {
return (associated.label!, associated.value)
}
print("WARNING: Enum option of \(self) does not have an associated value")
return ("\(self)", nil)
}
}
}
Then you can access the .asociated value with code like this:
class EVReflectionTests: XCTestCase {
func testEnumAssociatedValues() {
let parameters:[EVAssociated] = [usersParameters.number(19),
usersParameters.authors_only(false)]
let y = WordPressRequestConvertible.MeLikes("XX", Dictionary(associated: parameters))
// Now just extract the label and associated values from this enum
let label = y.associated.label
let (token, param) = y.associated.value as! (String, [String:Any]?)
XCTAssertEqual("MeLikes", label, "The label of the enum should be MeLikes")
XCTAssertEqual("XX", token, "The token associated value of the enum should be XX")
XCTAssertEqual(19, param?["number"] as? Int, "The number param associated value of the enum should be 19")
XCTAssertEqual(false, param?["authors_only"] as? Bool, "The authors_only param associated value of the enum should be false")
print("\(label) = {token = \(token), params = \(param)")
}
}
// See http://github.com/evermeer/EVWordPressAPI for a full functional usage of associated values
enum WordPressRequestConvertible: EVAssociated {
case Users(String, Dictionary<String, Any>?)
case Suggest(String, Dictionary<String, Any>?)
case Me(String, Dictionary<String, Any>?)
case MeLikes(String, Dictionary<String, Any>?)
case Shortcodes(String, Dictionary<String, Any>?)
}
public enum usersParameters: EVAssociated {
case context(String)
case http_envelope(Bool)
case pretty(Bool)
case meta(String)
case fields(String)
case callback(String)
case number(Int)
case offset(Int)
case order(String)
case order_by(String)
case authors_only(Bool)
case type(String)
}
The code above is now available as a cocoapod susbspec at
https://github.com/evermeer/Stuff#enum
It also has an other nice enum extension for enumerating all enum values.
If the associated values were of the same type for all enum cases the following approach could help.
enum Value {
case text(NSString!), two(NSString!), three(NSString!) // This could be any other type including AnyClass
}
// Emulating "fields" datastruct for demo purposes (as if we had struct with properties).
typealias Field = (en: Value, fieldName: String)
let fields: [Field] = [(.text(nil),"f1"), (.two(nil), "f2"), (.three("Hey"), "f3")] // this is analog of "fields"
let arrayOfFieldNamesWithEmptyEnums: [String] = fields.compactMap({
switch $0.en {
case let .text(foo), let .two(foo), let .three(foo): if foo == nil { return $0.fieldName } else { return nil }}
})
print("arrayOfFieldNamesWithEmptyEnums \(arrayOfFieldNamesWithEmptyEnums)")
Many other things can be obtained similarly.
let arrayOfEnumsWithoutValues: [Value] = fields.compactMap({
switch $0.en {
case let .text(foo), let .two(foo), let .three(foo): if foo == nil { return $0.en } else { return nil }}
})
print("arrayOfEnumsWithoutValues \(arrayOfEnumsWithoutValues)")
// just to check ourselves
if let index = arrayOfEnumsWithoutValues.index(where: { if case .two = $0 { return true }; return false }) {
print(".two found at index \(index)")
}

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