Getting String representation of Swift ReferenceWritableKeyPath is failed (returns pointer instead of type)

Question

alexgerm OP

Created Sep ’23

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Participants 2

I have a Product class inherited from Realm Object:

@objc class Product: Object {
    @Persisted(primaryKey: true) var id: String = ""
    @Persisted var externalId: String?
    @Persisted var name: String?
}

I try to write a universal method for objects update which takes dictionary with keyPaths and values and update object with this Realm method:

func setValue(_ value: Any?, forKey key: String)

This is a computed variable for getting String representation of KeyPath:

fileprivate extension KeyPath {
    var asString: String {
        let wholeString = String(describing: self)
        let dropLeading =  "\\" + String(describing: Root.self) + "."
        let keyPathString = "\(wholeString.dropFirst(dropLeading.count))"
        return keyPathString
    }
}

And it's perfectly works during debug mode, but when I build an app with Release scheme instead of "Product.name" it returns something like "\Product.<computed 0x000000010c51ed18 (Bool)> and the app crashed trying to set value for this keypath.

If anyone has idea how to fix this, it would be really appreciated.

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Answer 1

DTS Engineer OP

Apple

Sep ’23

There is, unhappily, no current way to get the string representation of a key path.

Using String(describing:) gets the key path's description, and as you've seen this is not a reliable way of getting the path. Even if it worked in release mode right now, it could break at any time in the future.

I suggest you continue discussing this over in the Swift forums (forums.swift.org). Extra visibility of the issue might help to get a solution a bit sooner.

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