Declare an array of Int in Realm Swift

Question

How can I declare an array of integers inside RLMObject?

Like :

dynamic var key:[Int]?

Gives the following error :

Terminating app due to uncaught exception 'RLMException', reason: ''NSArray' is not supported as an RLMObject property. All properties must be primitives, NSString, NSDate, NSData, RLMArray, or subclasses of RLMObject. See https://realm.io/docs/objc/latest/api/Classes/RLMObject.html for more information.'

score 44 · Accepted Answer · answered Feb 08 '16 at 11:00

44

Lists of primitives are not supported yet unfortunately. There is issue #1120 to track adding support for that. You'll find there some ideas how you can workaround that currently.

The easiest workaround is create a object to hold int values. Then the model to have a List of the object.

class Foo: Object {
    let integerList = List<IntObject>() // Workaround
}

class IntObject: Object {
    dynamic var value = 0
}

answered Feb 08 '16 at 11:00

kishikawa katsumi

10,418
1
41
53

34

This is just incredible that Realm doesn't support such a simple thing. – Frederic Adda Sep 08 '16 at 09:56
Is the support still not implemented? – Taichi Kato Mar 14 '17 at 13:44
Not yet. But Realm core team working hard now. It will be supported soon. – kishikawa katsumi Mar 14 '17 at 13:51
2

Looks like it is now supported, as of v3.0.0-beta.4 https://github.com/realm/realm-cocoa/releases/tag/v3.0.0-beta.4 – m_katsifarakis Oct 03 '17 at 10:13
No, it's not. I'm using v3.0.2. It still can't store List to database. – Kimi Chiu Jan 15 '18 at 08:07
2

@KimiChiu `List` should work from v3.0 https://realm.io/blog/realm-cocoa-reaches-3-0/ Probably you're something wrong. – kishikawa katsumi Jan 15 '18 at 08:09
@kishikawakatsumi You're right. It's working. I put a wrong value to the where clause. – Kimi Chiu Jan 15 '18 at 08:55

score 8 · Answer 2 · answered Mar 04 '19 at 12:55

8

Fortunately arrays of primitive types are now supported in Realm 3.0 and above. (Oct 31 2017)

You can now store primitive types or their nullable counterparts (more specifically: booleans, integer and floating-point number types, strings, dates, and data) directly within RLMArrays or Lists. If you want to define a list of such primitive values you no longer need to define cumbersome single-field wrapper objects. Instead, you can just store the primitive values themselves!

class MyObject : Object {
    @objc dynamic var myString: String = ""
    let myIntArray = List<Int>()
}

Source: https://realm.io/blog/realm-cocoa-reaches-3-0/

answered Mar 04 '19 at 12:55

Philipp Otto

4,061
2
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49

For what it's worth, if you choose to use a `List` of Primitives like this, you won't be able to filter `Results` using the `@count` predicate style as it's not supported on `List`s of Primitives . That said, wrapping them in Realm objects has it's own downsides... From https://docs.mongodb.com/realm/sdk/ios/examples/filter-data/: "Evaluates to the number of objects in the given collection. This is currently only supported on to-many relationship collections and not on lists of primitives. In order to use `@count` on a list of primitives, consider wrapping the primitives in a Realm object." – Ohifriend Aug 11 '21 at 00:00

MatanGold · Answer 3 · 2017-03-19T08:02:00.360

5

The accepted offer is very costly in term of memory. You might get a List of very big "n" of objects.

It's not a matter of right and wrong but I think it's good to write here a different workaround.

Another approach:
I decided to use a single string to represent an Int array.

In my Realm class I defined a variable:

dynamic var arrInt: String? = nil

And use it very easily:

let arrToSave = [0, 1, 33, 12232, 394]
<MY_CUSTOM_REALM_CLASS>.arrInt = arrToSave.map { String(describing: $0) }.joined(separator: ",")

And the way back:

let strFetched = <MY_CUSTOM_REALM_CLASS>.arrInt 
let intArray = strFetched.components(separatedBy: ",").flatMap { Int($0) }

Will be happy to hear your feedback, as I think this approach is better.

edited Mar 19 '17 at 08:02

answered Jan 25 '17 at 09:07

MatanGold

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Why the down vote? I presented this answer as a proposal that worked for me, if you don't like this solution, please share your thoughts, don't just down vote. – MatanGold Feb 12 '17 at 01:42
Using `description` is a very, very bad idea. Use this: to: `let stringOfArray = arrToSave.map { String(describing: $0) }.joined(separator: ",")`. From: `let intArray = stringOfArray.components(separatedBy: ",").flatMap { Int($0) }` – basvk Mar 17 '17 at 07:25

score 1 · Answer 4 · answered Feb 06 '16 at 08:55

1

As the error message states, you have to use RLMArray - or rather it's swift equivalent List.

See: Realm docs

answered Feb 06 '16 at 08:55

Lars Dahmen

11
3

Declare an array of Int in Realm Swift

4 Answers4