Fix duplicate saved instances not being uniqued correctly

Tusker.xcodeproj/project.pbxproj

@@ -288,6 +288,7 @@
 		D6C99FCB24FADC91005C74D3 /* MainComposeTextView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6C99FCA24FADC91005C74D3 /* MainComposeTextView.swift */; };
 		D6CA6A92249FAD8900AD45C1 /* AudioSessionHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6CA6A91249FAD8900AD45C1 /* AudioSessionHelper.swift */; };
 		D6CA6A94249FADE700AD45C1 /* GalleryPlayerViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6CA6A93249FADE700AD45C1 /* GalleryPlayerViewController.swift */; };
+		D6CA8CDA2962231F0050C433 /* ArrayUniqueTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6CA8CD92962231F0050C433 /* ArrayUniqueTests.swift */; };
 		D6D12B2F2925D66500D528E1 /* TimelineGapCollectionViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6D12B2E2925D66500D528E1 /* TimelineGapCollectionViewCell.swift */; };
 		D6D12B56292D57E800D528E1 /* AccountCollectionViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6D12B55292D57E800D528E1 /* AccountCollectionViewCell.swift */; };
 		D6D12B58292D5B2C00D528E1 /* StatusActionAccountListViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6D12B57292D5B2C00D528E1 /* StatusActionAccountListViewController.swift */; };
@@ -672,6 +673,7 @@
 		D6C99FCA24FADC91005C74D3 /* MainComposeTextView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MainComposeTextView.swift; sourceTree = "<group>"; };
 		D6CA6A91249FAD8900AD45C1 /* AudioSessionHelper.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AudioSessionHelper.swift; sourceTree = "<group>"; };
 		D6CA6A93249FADE700AD45C1 /* GalleryPlayerViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GalleryPlayerViewController.swift; sourceTree = "<group>"; };
+		D6CA8CD92962231F0050C433 /* ArrayUniqueTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ArrayUniqueTests.swift; sourceTree = "<group>"; };
 		D6D12B2E2925D66500D528E1 /* TimelineGapCollectionViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineGapCollectionViewCell.swift; sourceTree = "<group>"; };
 		D6D12B55292D57E800D528E1 /* AccountCollectionViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AccountCollectionViewCell.swift; sourceTree = "<group>"; };
 		D6D12B57292D5B2C00D528E1 /* StatusActionAccountListViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatusActionAccountListViewController.swift; sourceTree = "<group>"; };
@@ -1485,6 +1487,7 @@
 				D6E426AC25334DA500C02E1C /* FuzzyMatcherTests.swift */,
 				D6114E1627F8BB210080E273 /* VersionTests.swift */,
 				D61F75A029396DE200C0B37F /* SemiCaseSensitiveComparatorTests.swift */,
+				D6CA8CD92962231F0050C433 /* ArrayUniqueTests.swift */,
 				D6D4DDE6212518A200E1C4BB /* Info.plist */,
 			);
 			path = TuskerTests;
@@ -2136,6 +2139,7 @@
 				D62FF04823D7CDD700909D6E /* AttributedStringHelperTests.swift in Sources */,
 				D6E426AD25334DA500C02E1C /* FuzzyMatcherTests.swift in Sources */,
 				D6114E1727F8BB210080E273 /* VersionTests.swift in Sources */,
+				D6CA8CDA2962231F0050C433 /* ArrayUniqueTests.swift in Sources */,
 				D6D4DDE5212518A200E1C4BB /* TuskerTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Tusker/Extensions/Array+Uniques.swift

@@ -8,16 +8,31 @@
 
 import Foundation
 
+extension Array {
+    func uniques<ID: Hashable>(by identify: (Element) -> ID) -> [Element] {
+        var uniques = Set<Hashed<Element, ID>>()
+        for elem in self {
+            uniques.insert(Hashed(element: elem, id: identify(elem)))
+        }
+        return uniques.map(\.element)
+    }
+}
+
 extension Array where Element: Hashable {
     func uniques() -> [Element] {
-        var buffer = [Element]()
+        return uniques(by: { $0 })
-        var added = Set<Element>()
-        for elem in self {
-            if !added.contains(elem) {
-                buffer.append(elem)
-                added.insert(elem)
     }
 }
-        return buffer
+
+fileprivate struct Hashed<Element, ID: Hashable>: Hashable {
+    let element: Element
+    let id: ID
+    
+    static func ==(lhs: Self, rhs: Self) -> Bool {
+        return lhs.id == rhs.id
+    }
+    
+    func hash(into hasher: inout Hasher) {
+        hasher.combine(id)
     }
 }

Tusker/Screens/Explore/ExploreViewController.swift

@@ -216,7 +216,7 @@ class ExploreViewController: UIViewController, UICollectionViewDelegate, Collect
         let req = SavedInstance.fetchRequest(account: mastodonController.accountInfo!)
         req.sortDescriptors = [NSSortDescriptor(key: "url.host", ascending: true)]
         do {
-            return try mastodonController.persistentContainer.viewContext.fetch(req).uniques()
+            return try mastodonController.persistentContainer.viewContext.fetch(req).uniques(by: \.url)
         } catch {
             return []
         }

Tusker/Screens/Main/MainSidebarViewController.swift

@@ -250,7 +250,7 @@ class MainSidebarViewController: UIViewController {
         let req = SavedInstance.fetchRequest(account: mastodonController.accountInfo!)
         req.sortDescriptors = [NSSortDescriptor(key: "url.host", ascending: true)]
         do {
-            return try mastodonController.persistentContainer.viewContext.fetch(req).uniques()
+            return try mastodonController.persistentContainer.viewContext.fetch(req).uniques(by: \.url)
         } catch {
             return []
         }

TuskerTests/ArrayUniqueTests.swift

@@ -0,0 +1,45 @@
+//
+//  ArrayUniqueTests.swift
+//  TuskerTests
+//
+//  Created by Shadowfacts on 1/1/23.
+//  Copyright © 2023 Shadowfacts. All rights reserved.
+//
+
+import XCTest
+@testable import Tusker
+
+final class ArrayUniqueTests: XCTestCase {
+    
+    func testUniquesBy() {
+        let a = Test(string: "test")
+        let b = Test(string: "test")
+        XCTAssertNotEqual(a.id, b.id)
+        XCTAssertNotEqual(a.hashValue, b.hashValue)
+        XCTAssertEqual([a, b].uniques(by: \.string), [a])
+    }
+    
+    class Test: NSObject {
+        let id = UUID()
+        let string: String
+        
+        init(string: String) {
+            self.string = string
+        }
+        
+        override func isEqual(_ object: Any?) -> Bool {
+            guard let other = object as? Self else {
+                return false
+            }
+            return id == other.id && string == other.string
+        }
+        
+        override var hash: Int {
+            var hasher = Hasher()
+            hasher.combine(id)
+            hasher.combine(string)
+            return hasher.finalize()
+        }
+    }
+
+}