Best way to implement Enums with Core Data

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What is the best way to bind Core Data entities to enum values so that I am able to assign a type property to the entity? In other words, I have an entity called Item with an itemType property that I want to be bound to an enum, what is the best way of going about this.

core-data objective-c cocoa iphone cocoa-touch
9 Answers

Solution for Auto Generated Classes

from Xcode's Code Generator (ios 10 and above)

If you create an Entity named "YourClass", Xcode automatically will choose "Class Definition" as default a Codegen type at "Data Model Inspector". this will generate classes below:

Swift version:

// YourClass+CoreDataClass.swift
  @objc(YourClass)
  public class YourClass: NSManagedObject {
  }

Objective-C version:

// YourClass+CoreDataClass.h
  @interface YourClass : NSManagedObject
  @end

  #import "YourClass+CoreDataProperties.h"

  // YourClass+CoreDataClass.m
  #import "YourClass+CoreDataClass.h"
  @implementation YourClass
  @end

We'll choose "Category/Extension" from Codegen option instead of "Class Definition" in Xcode.

Now, If we want to add an enum, go and create another extension for your auto-generated class, and add your enum definitions here like below:

// YourClass+Extension.h

#import "YourClass+CoreDataClass.h" // That was the trick for me!

@interface YourClass (Extension)

@end


// YourClass+Extension.m

#import "YourClass+Extension.h"

@implementation YourClass (Extension)

typedef NS_ENUM(int16_t, YourEnumType) {
    YourEnumTypeStarted,
    YourEnumTypeDone,
    YourEnumTypePaused,
    YourEnumTypeInternetConnectionError,
    YourEnumTypeFailed
};

@end

Now, you can create custom accessors if you want to restrict the values to an enum. Please check the accepted answer by question owner. Or you can convert your enums while you set them with explicitly conversion method using the cast operator like below:

model.yourEnumProperty = (int16_t)YourEnumTypeStarted;

Also check

Xcode automatic subclass generation

Xcode now supports automatic generation of NSManagedObject subclasses in the modeling tool. In the entity inspector:

Manual/None is the default, and previous behavior; in this case, you should implement your own subclass or use NSManagedObject. Category/Extension generates a class extension in a file named like ClassName+CoreDataGeneratedProperties. You need to declare/implement the main class (if in Obj-C, via a header the extension can import named ClassName.h). Class Definition generates subclass files named like ClassName+CoreDataClass as well as the files generated for Category/Extension. The generated files are placed in DerivedData and rebuilt on the first build after the model is saved. They are also indexed by Xcode, so command-clicking on references and fast-opening by filename works.

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