Somewhat working file tray

DynamicIsland/helpers/AssociatedObject.swift

@@ -0,0 +1,28 @@
+//
+//  AssociatedObject.swift
+//  DynamicIsland
+//
+//  Helper for retaining objects via Objective-C associated storage.
+//
+
+import Foundation
+import ObjectiveC
+
+public struct AssociatedObject<Value: AnyObject> {
+    private let key: UnsafeRawPointer
+    private let policy: objc_AssociationPolicy
+
+    public init(_ policy: objc_AssociationPolicy = .OBJC_ASSOCIATION_RETAIN_NONATOMIC) {
+        self.key = UnsafeRawPointer(Unmanaged.passUnretained(UniqueKey()).toOpaque())
+        self.policy = policy
+    }
+
+    private final class UniqueKey {}
+
+    public subscript<Owner: AnyObject>(_ owner: Owner) -> Value? {
+        get { objc_getAssociatedObject(owner, key) as? Value }
+        nonmutating set { objc_setAssociatedObject(owner, key, newValue, policy) }
+    }
+}
+
+extension AssociatedObject: @unchecked Sendable where Value: Sendable {}