Override open variable for class in Swift and SpriteKit for use in XCode's ActionEditor

I'm trying to make small platformer game, just in learning purposes. I've tried to animate character with array of SKTextures like this:

let animation: SKAction = SKAction.animate(
    with: frames.map {
        let texture : SKTexture = SKTexture(imageNamed: $0)
        texture.filteringMode = SKTextureFilteringMode.nearest

        return texture
    },
    timePerFrame: 0.15
)

frames variable is array of SKTextures. I've used map to set filtering mode for each texture. This works fine and dandy, but than i've discovered that i can create animations (actions) in ActionEditor in XCode with AnimateWithTextures action. And here lies my problem. This is much more efficient, but i can't change filtering mode for textures in animation in ActionEditor. I've looked into SKTexture class and saw this:

open class SKTexture : NSObject, NSCopying, NSCoding {
    ...
    /**
    The filtering mode the texture should use when not drawn at native size. Defaults to SKTextureFilteringLinear.
    */
    open var filteringMode: SKTextureFilteringMode
    ...
}

If i'm not mistaken open means that i can override variable, but i don't know how. I want to set default value of filteringMode to SKTextureFilteringMode.nearest for all SKTextures so ActionEditor will use textures with texture filtering set to nearest neighbor.

Also if you know how to set filtering mode for textures in specific action – i would like to know how to do it too. Thanks