Exception thrown in NSOrderedSet generated accessors

On my Lion app, I have this data model:

The relationship subitems inside Item is ordered.

Xcode 4.1 (build 4B110) has created for me the file Item.h, Item.m, SubItem.h and SubItem.h.

Here is the content (autogenerated) of Item.h:

#import <Foundation/Foundation.h>

#import <CoreData/CoreData.h>

@class SubItem;

@interface Item : NSManagedObject {
@private
}

@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSOrderedSet *subitems;
@end

@interface Item (CoreDataGeneratedAccessors)

- (void)insertObject:(SubItem *)value inSubitemsAtIndex:(NSUInteger)idx;
- (void)removeObjectFromSubitemsAtIndex:(NSUInteger)idx;
- (void)insertSubitems:(NSArray *)value atIndexes:(NSIndexSet *)indexes;
- (void)removeSubitemsAtIndexes:(NSIndexSet *)indexes;
- (void)replaceObjectInSubitemsAtIndex:(NSUInteger)idx withObject:(SubItem *)value;
- (void)replaceSubitemsAtIndexes:(NSIndexSet *)indexes withSubitems:(NSArray *)values;
- (void)addSubitemsObject:(SubItem *)value;
- (void)removeSubitemsObject:(SubItem *)value;
- (void)addSubitems:(NSOrderedSet *)values;
- (void)removeSubitems:(NSOrderedSet *)values;

@end

And here is the content (autogenerated) of Item.m:

#import "Item.h"
#import "SubItem.h"

@implementation Item

@dynamic name;
@dynamic subitems;

@end

As you can see, the class Item offers a method called addSubitemsObject:. Unfortunately, when trying to use it in this way:

Item *item = [NSEntityDescription insertNewObjectForEntityForName:@"Item" inManagedObjectContext:self.managedObjectContext];
item.name = @"FirstItem";

SubItem *subItem = [NSEntityDescription insertNewObjectForEntityForName:@"SubItem" inManagedObjectContext:self.managedObjectContext];

[item addSubitemsObject:subItem];

this error appear:

2011-09-12 10:28:45.236 Test[2002:707] *** -[NSSet intersectsSet:]: set argument is not an NSSet

Can you help me?

Update:

After just 1,787 days from my bug report, today (August 1, 2016) Apple wrote me this: "Please verify this issue with the latest iOS 10 beta build and update your bug report at bugreport.apple.com with your results.". Let's hope this is the right time :)

I reproduced your setup both with your data model and one of my own with different names. I got the same error in both cases.

Looks like a bug in Apple's autogenerated code.

I agree that there may be a bug here. I've modified the implementation of the add object setter to append correctly to a NSMutableOrderedSet.

- (void)addSubitemsObject:(SubItem *)value {
    NSMutableOrderedSet* tempSet = [NSMutableOrderedSet orderedSetWithOrderedSet:self.subitems];
    [tempSet addObject:value];
    self.subitems = tempSet;
}

Reassigning the set to self.subitems will ensure that the Will/DidChangeValue notifications are sent.

I've decided to improve the solution by implementing all the required methods:

static NSString *const kItemsKey = @"<#property#>";

- (void)insertObject:(<#Type#> *)value in<#Property#>AtIndex:(NSUInteger)idx {
    NSIndexSet* indexes = [NSIndexSet indexSetWithIndex:idx];
    [self willChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:kItemsKey];
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    [tmpOrderedSet insertObject:value atIndex:idx];
    [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
    [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:kItemsKey];
}

- (void)removeObjectFrom<#Property#>AtIndex:(NSUInteger)idx {
    NSIndexSet* indexes = [NSIndexSet indexSetWithIndex:idx];
    [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:kItemsKey];
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    [tmpOrderedSet removeObjectAtIndex:idx];
    [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
    [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:kItemsKey];
}

- (void)insert<#Property#>:(NSArray *)values atIndexes:(NSIndexSet *)indexes {
    [self willChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:kItemsKey];
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    [tmpOrderedSet insertObjects:values atIndexes:indexes];
    [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
    [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:kItemsKey];
}

- (void)remove<#Property#>AtIndexes:(NSIndexSet *)indexes {
    [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:kItemsKey];
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    [tmpOrderedSet removeObjectsAtIndexes:indexes];
    [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
    [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:kItemsKey];
}

- (void)replaceObjectIn<#Property#>AtIndex:(NSUInteger)idx withObject:(<#Type#> *)value {
    NSIndexSet* indexes = [NSIndexSet indexSetWithIndex:idx];
    [self willChange:NSKeyValueChangeReplacement valuesAtIndexes:indexes forKey:kItemsKey];
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    [tmpOrderedSet replaceObjectAtIndex:idx withObject:value];
    [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
    [self didChange:NSKeyValueChangeReplacement valuesAtIndexes:indexes forKey:kItemsKey];
}

- (void)replace<#Property#>AtIndexes:(NSIndexSet *)indexes with<#Property#>:(NSArray *)values {
    [self willChange:NSKeyValueChangeReplacement valuesAtIndexes:indexes forKey:kItemsKey];
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    [tmpOrderedSet replaceObjectsAtIndexes:indexes withObjects:values];
    [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
    [self didChange:NSKeyValueChangeReplacement valuesAtIndexes:indexes forKey:kItemsKey];
}

- (void)add<#Property#>Object:(<#Type#> *)value {
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    NSUInteger idx = [tmpOrderedSet count];
    NSIndexSet* indexes = [NSIndexSet indexSetWithIndex:idx];
    [self willChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:kItemsKey];
    [tmpOrderedSet addObject:value];
    [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
    [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:kItemsKey];
}

- (void)remove<#Property#>Object:(<#Type#> *)value {
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    NSUInteger idx = [tmpOrderedSet indexOfObject:value];
    if (idx != NSNotFound) {
        NSIndexSet* indexes = [NSIndexSet indexSetWithIndex:idx];
        [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:kItemsKey];
        [tmpOrderedSet removeObject:value];
        [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
        [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:kItemsKey];
    }
}

- (void)add<#Property#>:(NSOrderedSet *)values {
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    NSMutableIndexSet *indexes = [NSMutableIndexSet indexSet];
    NSUInteger valuesCount = [values count];
    NSUInteger objectsCount = [tmpOrderedSet count];
    for (NSUInteger i = 0; i < valuesCount; ++i) {
        [indexes addIndex:(objectsCount + i)];
    }
    if (valuesCount > 0) {
        [self willChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:kItemsKey];
        [tmpOrderedSet addObjectsFromArray:[values array]];
        [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
        [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:kItemsKey];
    }
}

- (void)remove<#Property#>:(NSOrderedSet *)values {
    NSMutableOrderedSet *tmpOrderedSet = [NSMutableOrderedSet orderedSetWithOrderedSet:[self mutableOrderedSetValueForKey:kItemsKey]];
    NSMutableIndexSet *indexes = [NSMutableIndexSet indexSet];
    for (id value in values) {
        NSUInteger idx = [tmpOrderedSet indexOfObject:value];
        if (idx != NSNotFound) {
            [indexes addIndex:idx];
        }
    }
    if ([indexes count] > 0) {
        [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:kItemsKey];
        [tmpOrderedSet removeObjectsAtIndexes:indexes];
        [self setPrimitiveValue:tmpOrderedSet forKey:kItemsKey];
        [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:kItemsKey];
    }
}

Yes, this is definitely a Core Data bug. I wrote up an ObjC-Runtime-based fix a while back, but at the time I figured it would be fixed soon. Anyway, no such luck, so I posted it up on GitHub as KCOrderedAccessorFix. Work around the problem on all your entities:

[managedObjectModel kc_generateOrderedSetAccessors];

One entity in particular:

[managedObjectModel kc_generateOrderedSetAccessorsForEntity:entity];

Or just for one relationship:

[managedObjectModel kc_generateOrderedSetAccessorsForRelationship:relationship];

Instead to making a copy I suggest to use the accessor in NSObject to get access to the NSMutableOrderedSet of the relationships.

- (void)addSubitemsObject:(SubItem *)value {
      NSMutableOrderedSet* tempSet = [self mutableOrderedSetValueForKey:@"subitems"];
      [tempSet addObject:value];
 }

e.g. the Core Data Release Notes for iOS v5.0 refer to this.

In a short test it worked in my application.

I've tracked the bug. It occurs in willChangeValueForKey:withSetMutation:usingObjects:.

This call sets off a chain of notifications which may be difficult to track, and of course changes to one responder may have implications for another, which I suspect is why Apple have done nothing.

However, it is okay in Set and its only the Set operations on an OrderedSet that malfunction. That means there are only four methods that need to be altered. Therefore, all I did was convert the Set operations to their equivalent Array operations. These work perfectly and minimal (but necessary) overheads.

On a critical level, this solution does suffer from one critical flaw; if you are adding objects and one of the objects already exists, then it is either not added or moved to the back of the ordered list (I don't know which). In either case, the expected ordered index of the object by the time we arrive at didChange is different from what was anticipated. This may break some people's apps, but it doesn't affect mine, since I am only ever adding new objects or I confirm their final locations before I add them.

- (void)addChildrenObject:(BAFinancialItem *)value {
    if ([self.children containsObject:value]) {
        return;
    }
    NSIndexSet * indexSet = [NSIndexSet indexSetWithIndex:self.children.count];
    [self willChange:NSKeyValueChangeInsertion valuesAtIndexes:indexSet forKey:ChildrenKey];
    [[self primitiveValueForKey:ChildrenKey] addObject:value];
    [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:indexSet forKey:ChildrenKey];
}

- (void)removeChildrenObject:(BAFinancialItem *)value {
    if (![self.children containsObject:value]) {
        return;
    }
    NSIndexSet * indexSet = [NSIndexSet indexSetWithIndex:[self.children indexOfObject:value]];
    [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:indexSet forKey:ChildrenKey];
    [[self primitiveValueForKey:ChildrenKey] removeObject:value];
    [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:indexSet forKey:ChildrenKey];
}

- (void)addChildren:(NSOrderedSet *)values {
    if ([values isSubsetOfOrderedSet:self.children]) {
        return;
    }
    NSIndexSet * indexSet = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(self.children.count, values.count)];
    [self willChange:NSKeyValueChangeInsertion valuesAtIndexes:indexSet forKey:ChildrenKey];
    [[self primitiveValueForKey:ChildrenKey] unionOrderedSet:values];
    [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:indexSet forKey:ChildrenKey];
}

- (void)removeChildren:(NSOrderedSet *)values {
    if (![self.children intersectsOrderedSet:values]) {
        return;
    }
    NSIndexSet * indexSet = [self.children indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
        return [values containsObject:obj];
    }];
    [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:indexSet forKey:ChildrenKey];
    [[self primitiveValueForKey:ChildrenKey] minusOrderedSet:values];
    [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:indexSet forKey:ChildrenKey];
}

Of course, there is an easier solution. it is as follows;

- (void)addChildrenObject:(BAFinancialItem *)value {
    if ([self.children containsObject:value]) {
        return;
    }
    [self insertObject:value inChildrenAtIndex:self.children.count];
}

- (void)removeChildrenObject:(BAFinancialItem *)value {
    if (![self.children containsObject:value]) {
        return;
    }
    [self removeObjectFromChildrenAtIndex:[self.children indexOfObject:value]];
}

- (void)addChildren:(NSOrderedSet *)values {
    if ([values isSubsetOfOrderedSet:self.children]) {
        return;
    }
    [self insertChildren:values atIndexes:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(self.children.count, values.count)]];
}

- (void)removeChildren:(NSOrderedSet *)values {
    if (![self.children intersectsOrderedSet:values]) {
        return;
    }
    [self removeChildrenAtIndexes:[self.children indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
        return [values containsObject:obj];
    }]];
}

The [Apple docs To Many Relations][1] says: you should access the proxy mutable set or ordered set using

NSMutableOrderedSet * set = [managedObject mutableOrderedSetValueForKey:@"toManyRelation"];

Modifying this set will add or remove relations to your managed object. Accessing the mutable ordered set using the accessor whether with [ ] or . notation is wrong and will fail. [1]: https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreData/Articles/cdUsingMOs.html#//apple_ref/doc/uid/TP40001803-SW3

Received the same error, @LeeIII solution worked for me (thanks!). I suggest slightly modify it:

• use objective-c category to store the new method (so we wont lose our method if Item is generated again)
• check if we already have mutable set

Content of Item+category.m:

#import "Item+category.h"

@implementation Item (category)

- (void)addSubitemsObject:(SubItem *)value {
    if ([self.subitems isKindOfClass:[NSMutableOrderedSet class]]) {
        [(NSMutableOrderedSet *)self.subitems addObject:value];
    } else {
        NSMutableOrderedSet* tempSet = [NSMutableOrderedSet orderedSetWithOrderedSet:self.subitems];
        [tempSet addObject:value];
        self.subitems = tempSet;
    }
}

@end

If you are using mogenerator, then instead of

[parentObject add<Child>sObject:childObject];

simply use:

[[parent object <child>sSet] addObject:childObject];

Personally I have just replaced the calls to the CoreData generated methods with direct calls to the method as outlined in another solution by @Stephan:

NSMutableOrderedSet* tempSet = [self mutableOrderedSetValueForKey:@"subitems"];
      [tempSet addObject:value];
[tempSet addObject:value];

This removes the need for categories that might later conflict with a solution from Apple to the generated code when the bug is fixed.

This has the added plus of being the official way to do it!

It seems that if you link the parent with the child by setting the parent to the child and not the other way around it works without crashing.

So if you do:

[child setParent:parent]

instead of

[parent setChildObects:child]

It should work, at least it works on iOS 7 and didn't had any problems with the relationship.

>I agree that there maybe a bug here. I've modified the implementation of the add object >setter to append correctly to a NSMutableOrderedSet. > > - (void)addSubitemsObject:(SubItem )value { > NSMutableOrderedSet tempSet = [NSMutableOrderedSet orderedSetWithOrderedSet:self.subitems]; > [tempSet addObject:value]; > self.subitems = tempSet; > } >Reassigning the set to self.subitems will ensure that the Will/DidChangeValue notifications >are sent.

Leelll, are you sure that after such custom setup of NSMutableOrderedSet values stored in that set will be saved to the database correctly by CoreData? I didn't check that, but it looks like CoreData knows nothing about NSOrderedSet and expects NSSet as to-many relationship container.

I have had the same problem, but only when I tried something different to what I had been doing. I can't see the code for subItem, but I will assume that it has a reverse link to item. Lets call this reveres link, "parentItem", then the easiest solution is this:

Item *item = [NSEntityDescription insertNewObjectForEntityForName:@"Item" inManagedObjectContext:self.managedObjectContext];
item.name = @"FirstItem";

SubItem *subItem = [NSEntityDescription insertNewObjectForEntityForName:@"SubItem" inManagedObjectContext:self.managedObjectContext];

//[item addSubitemsObject:subItem];
subItem.parentItem = item;

The effect is that it makes use of apple's own code and it is simple and clean. In addition, the set is automatically added to, and all observers are updated. No problem.

I just fell foul of this issue, and resolved it using a much simpler implementation than the others outlined here. I simply make use of the methods available on NSManagedObject for dealing with relationships when not using subclasses.

An example implementation for inserting an entity into an NSOrderedSet relationship would look like this:

- (void)addAddress:(Address *)address
{
    if ([self.addresses containsObject:address]) {
        return;
    }
    // Use NSManagedObject's methods for inserting an object
    [[self mutableOrderedSetValueForKey:@"addresses"] addObject:address];
}

This works perfectly, and is what I was using before I moved to NSManagedObject subclasses.

This issue occurred to me while migrating a project from Objective-C to Swift 2 with XCode 7. That project used to work, and for a good reason: I was using MOGenerator which had replacement methods to fix this bug. But not all methods require a replacement.

So here's the complete solution with an example class, relying on default accessors as much as possible.

Let's say we have a List with ordered Items

First a quick win if you have a one/to-many relationship, the easiest is to just do:

item.list = list

instead of

list.addItemsObject(item)

Now, if that's not an option, here's what you can do:

// Extension created from your DataModel by selecting it and
// clicking on "Editor > Create NSManagedObject subclass…"

extension List {
  @NSManaged var items: NSOrderedSet?
}

class List
  
  // Those two methods work out of the box for free, relying on
  // Core Data's KVC accessors, you just have to declare them
  // See release note 17583057 https://developer.apple.com/library/prerelease/tvos/releasenotes/DeveloperTools/RN-Xcode/Chapters/xc7_release_notes.html
  @NSManaged func removeItemsObject(item: Item)
  @NSManaged func removeItems(items: NSOrderedSet)

  // The following two methods usually work too, but not for NSOrderedSet
  // @NSManaged func addItemsObject(item: Item)
  // @NSManaged func addItems(items: NSOrderedSet)

  // So we'll replace them with theses

  // A mutable computed property
  var itemsSet: NSMutableOrderedSet {
    willAccessValueForKey("items")
    let result = mutableOrderedSetValueForKey("items")
    didAccessValueForKey("items")
    return result
  }
    
  func addItemsObject(value: Item) {
    itemsSet.addObject(value)
  }
    
  func addItems(value: NSOrderedSet) {
    itemsSet.unionOrderedSet(value)
  }
end

Of course, if you're using Objective-C, you can do the exact same thing since this is where I got the idea in the first place :)

I think everybody is missing the real problem. It is not in the accessor methods but rather in the fact that NSOrderedSet is not a subclass of NSSet. So when -interSectsSet: is called with an ordered set as argument it fails.

NSOrderedSet* setA = [NSOrderedSet orderedSetWithObjects:@"A",@"B",@"C",nil];
NSSet* setB = [NSSet setWithObjects:@"C",@"D", nil];

 [setB intersectsSet:setA];

fails with *** -[NSSet intersectsSet:]: set argument is not an NSSet

Looks like the fix is to change the implementation of the set operators so they handle the types transparently. No reason why a -intersectsSet: should work with either an ordered or unordered set.

The exception happens in the change notification. Presumably in the code that handles the inverse relationship. Since it only happens if I set an inverse relationship.

The following did the trick for me

@implementation MF_NSOrderedSetFixes

+ (void) fixSetMethods
{
    NSArray* classes = [NSArray arrayWithObjects:@"NSSet", @"NSMutableSet", @"NSOrderedSet", @"NSMutableOrderedSet",nil];

    [classes enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {        NSString* name = obj;        Class aClass = objc_lookUpClass([name UTF8String]);
        [MF_NSOrderedSetFixes fixMethodWithSetArgument:@selector(intersectsSet:) forClass:aClass];
        [MF_NSOrderedSetFixes fixMethodWithSetArgument:@selector(isSubsetOfSet:) forClass:aClass];
    }];
}

typedef BOOL (*BoolNSetIMP)(id _s,SEL sel, NSSet*);

/*
    Works for all methods of type - (BOOL) method:(NSSet*) aSet
*/
+ (void) fixMethodWithSetArgument:(SEL) aSel forClass:(Class) aClass 
{
    /* Check that class actually implements method first */
    /* can't use get_classInstanceMethod() since it checks superclass */
    unsigned int count,i;
    Method method = NULL;
    Method* methods = class_copyMethodList(aClass, &count);
    if(methods) {
        for(i=0;i<count;i++) {
            if(method_getName(methods[i])==aSel) {
                method = methods[i];
            }
        }
        free(methods);
    }
    if(!method) {
        return;
    }
    
   // Get old implementation
   BoolNSetIMP originalImp  = (BoolNSetIMP) method_getImplementation(method);
   IMP newImp = imp_implementationWithBlock(^BOOL(NSSet *_s, NSSet *otherSet) {
        if([otherSet isKindOfClass:[NSOrderedSet class]]) {
            otherSet = [(NSOrderedSet*)otherSet set];
        }
        // Call original implementation
        return originalImp(_s,aSel,otherSet);
    });
    method_setImplementation(method, newImp);
}
@end

I just got the problem in Swift (Xcode 6.1.1).

The answer was DO NOT CODE ANY METHOD OR ADDITIONAL THINGS in your NSManagedObject subclasses. I think it is a compilator mistake. Very strange bug ..

Hope it helps ..

I solved this problem by set the inverse to No Inverse, I don't know why, Maybe there is Apple Bug.

I have the same situation with an item called "signals" instead of "subitems". The solution with tempset works in my testing. Further, I had a problem with the removeSignals: method. This override seems to work:

- (void)removeSignals:(NSOrderedSet *)values {
    NSMutableOrderedSet* tempset = [NSMutableOrderedSet orderedSetWithOrderedSet:self.signals];
    for (Signal* aSignal in values) {
        [tempset removeObject:aSignal];
    }
    self.signals = tempset;
}

If there is a better way to do this, please let me know. My values input is never more than 10 -20 items so performance isn't much of a concern - nonetheless please point out anything relevant.

Thanks,

Damien

I found a fix for this bug that works for me. I just replace this:

[item addSubitemsObject:subItem];

with this:

item.subitemsObject = subItem;

I found this question by googling for the error message, and just wanted to point out that I ran into this error in a slightly different way (not using ordered sets). This isn't quite an answer to the given question, but I'm posting it here just in case it is helpful to anyone else who stumbles across this question while searching.

I was adding a new model version, and added some relationships to existing models, and defined the add*Object methods in the header file myself. When I tried to call them, I got the error above.

After reviewing my models, I realized I had stupidly forgotten to check the "To-Many Relationship" checkbox.

So if you're running into this and you're not using ordered sets, double check your model.

Better version of the correct answer in SWIFT

var tempSet = NSMutableOrderedSet()
if parent!.subItems != nil {
    tempSet = NSMutableOrderedSet(orderedSet: parent!.subItems!)
}
                
tempSet.add(newItem)
parent!.subItems = tempSet

I found using the method by LeeIII worked, but on profiling found it was drastically slow. It took 15 seconds to parse 1000 items. Commenting out the code to add the relationship turned 15 seconds into 2 seconds.

My workaround (which is faster but much more ugly) involves creating a temporary mutable array then copying into the ordered set when all the parsing is done. (this is only a performance win if you are going to add many relationships).

@property (nonatomic, retain) NSMutableArray* tempItems;
 ....
@synthesize tempItems = _tempItems;
 ....

- (void) addItemsObject:(KDItem *)value 
{
    if (!_tempItems) {
        self.tempItems = [NSMutableArray arrayWithCapacity:500];
    }
    [_tempItems addObject:value];
}

// Call this when you have added all the relationships
- (void) commitRelationships 
{
    if (_tempItems) {
        self.items = [NSOrderedSet orderedSetWithArray:self.tempItems];
        self.tempItems = nil;
    }
}

I hope this help someone else!

Robert,

I agree your answer will work for this, but keep in mind that there is an automatically created method for adding a whole set of values to a relationship already. Apple's Documentation (as seen here under the "To-many Relationships" section or here under the "Custom To-Many Relationship Accessor Methods" section) implements them this way:

- (void)addEmployees:(NSSet *)value
{
[self willChangeValueForKey:@"employees"
      withSetMutation:NSKeyValueUnionSetMutation
      usingObjects:value];
[[self primitiveEmployees] unionSet:value];
[self didChangeValueForKey:@"employees"
      withSetMutation:NSKeyValueUnionSetMutation
      usingObjects:value];
}

- (void)removeEmployees:(NSSet *)value
{
[self willChangeValueForKey:@"employees"
      withSetMutation:NSKeyValueMinusSetMutation
      usingObjects:value];
[[self primitiveEmployees] minusSet:value];
[self didChangeValueForKey:@"employees"
      withSetMutation:NSKeyValueMinusSetMutation
      usingObjects:value];
}

You could easily compile your set of relationships outside of core data and then add them all at once using this method. It might be less ugly than the method you suggested ;)

I'm quite sure it is finally fixed in iOS 10 beta 6!