# Overriding AnyObject to a more specific type

**URL:** <https://forums.kodeco.com/t/overriding-anyobject-to-a-more-specific-type/13392>\
**Category:** Swift\
**Created:** [April 14, 2016, 4:51pm UTC](https://forums.kodeco.com/t/overriding-anyobject-to-a-more-specific-type/13392 "2016-04-14T16:51:42Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![frankieshakes](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/frankieshakes/32/81494_2.png) [@frankieshakes](https://forums.kodeco.com/u/frankieshakes)\
**Post date:** [April 14, 2016, 4:51pm UTC](https://forums.kodeco.com/t/overriding-anyobject-to-a-more-specific-type/13392/1 "2016-04-14T16:51:42Z")

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Hi there,

I’ve hit a bit of a wall on trying to figure out how best to solve the following situation:

I’ve got a protocol that requires the following method for all objects that implement it:

`protocol OperationDataProvider { func provideData() -> OperationResultType? } `

I’m trying to declare several “types” that all behave in a similar fashion. I’ve created the following protocol in hopes that each type that implements it can override the “AnyObject” defined within the protocol:

` protocol OperationResultType { var result: AnyObject? { get } var error: NSError? { get } }`

I’m then trying to create other types that can specify the type of “result”:

`TestOperationResult<T>: OperationResultType { var result: T? var error: NSError? }`

I’m using a generic to try and infer the type based on the type when the TestOperationResult is created.

Unfortunately, I’m running into an issue as it doesn’t appear that I can override `result` to be anything other than `AnyObject`

Is it possible to achieve what I’m attempting to do?

Any help and/or direction would be very much appreciated.

Thank you!  
Frank

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<div class="post-metadata">

**Author:** ![aeberbach](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/aeberbach/32/81494_2.png) [@aeberbach](https://forums.kodeco.com/u/aeberbach)\
**Post date:** [April 15, 2016, 12:24am UTC](https://forums.kodeco.com/t/overriding-anyobject-to-a-more-specific-type/13392/2 "2016-04-15T00:24:08Z")

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I would always use OperationResultType there instead of AnyObject. Essentially it is still a generic but one guaranteed to conform to the protocol, which is what you want.

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**Author:** ![narrativium](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/narrativium/32/110937_2.png) [@narrativium](https://forums.kodeco.com/u/narrativium)\
**Post date:** [April 15, 2016, 9:39am UTC](https://forums.kodeco.com/t/overriding-anyobject-to-a-more-specific-type/13392/3 "2016-04-15T09:39:48Z")

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If each conformer to OperationResultType should be able to specify its type of result, then in principle you would need an associated type.

```swift
protocol OperationResultType {
  associatedtype Result : AnyObject
  var result : Result? { get }
  var error: NSError? { get } 
}

```

However, it’s not quite that simple, because `OperationDataProvider.provideData()` can’t now return an OperationResultType any more than it could return an `Equatable` or an `Optional` - it has ‘Self’ requirements - and you need to know what the associated type is to make use of it. (e.g. instead of `provideData` you might need a `provideIntData` to return an `OperationResultType` whose result was of type `Int`). You can make generic types, but you can’t use them to hide what the type is.