add a minimal LLM chat example + switch to mlx-swift 0.30.2 (#454)

* add a minimal LLM chat example

- LLMEval has more of a showcase of features and runtime statistics
- this provides the minimum required to load a model and interact with it
- also cleans up the xcodeproj (see #451)
- removes VLMEval (redundant and wasn't maintained)

* remove tests that have migrated to mlx-swift-lm
* remove ExampleLLM -- this will be covered by other examples
* rework llm-tool to use ChatSession -- a better example

* workaround for CI failures

* update to mlx-swift 0.30.3 and mlx-swift-lm 2.30.3

Author: davidkoski

.github/workflows/pull_request.yml

@@ -1,6 +1,6 @@
 name: Build and Test
 
-on: pull_request  
+on: pull_request
 
 permissions:
   contents: read
@@ -14,13 +14,13 @@ jobs:
     steps:
       - uses: actions/checkout@v6
         with:
-          submodules: recursive           
+          submodules: recursive
 
       - name: Setup uv
         uses: astral-sh/setup-uv@v6
         with:
-            activate-environment: true
-     
+          activate-environment: true
+
       - name: Setup pre-commit
         shell: sh
         run: |
@@ -58,17 +58,16 @@ jobs:
         run: |
           cd /tmp/swift-format
           ln -s "$(swift build --show-bin-path -c release)/swift-format" /usr/local/bin/swift-format
-     
+
       - name: Configure safe directory for git
         shell: sh
         run: |
           git config --global --add safe.directory "$GITHUB_WORKSPACE"
-     
+
       - name: Run style checks
         shell: sh
         run: |
           pre-commit run --all || (echo "Style checks failed, please install pre-commit and run pre-commit run --all and push the change"; echo ""; git --no-pager diff; exit 1)
-      
 
   mac_build_and_test:
     needs: lint
@@ -78,13 +77,19 @@ jobs:
       - uses: actions/checkout@v6
         with:
           submodules: recursive
-     
+
       - name: Verify MetalToolchain installed
         shell: bash
+        env:
+          # workaround for CI failure
+          DEVELOPER_DIR: /Applications/Xcode-latest.app
         run: xcodebuild -showComponent MetalToolchain
-            
+
       - name: Build Package (Xcode, macOS)
         shell: sh
+        env:
+          # workaround for CI failure
+          DEVELOPER_DIR: /Applications/Xcode-latest.app
         run: |
           xcodebuild -version
           xcrun --show-sdk-build-version
@@ -94,6 +99,9 @@ jobs:
 
       - name: Build tools (Xcode, macOS)
         shell: sh
+        env:
+          # workaround for CI failure
+          DEVELOPER_DIR: /Applications/Xcode-latest.app
         run: |
           xcodebuild -version
           xcrun --show-sdk-build-version

…ssets/AccentColor.colorset/Contents.json …ssets/AccentColor.colorset/Contents.jsonApplications/VLMEval/Assets.xcassets/AccentColor.colorset/Contents.json renamed to Applications/LLMBasic/Assets.xcassets/AccentColor.colorset/Contents.json Applications/VLMEval/Assets.xcassets/AccentColor.colorset/Contents.json renamed to Applications/LLMBasic/Assets.xcassets/AccentColor.colorset/Contents.json

@@ -0,0 +1,85 @@
+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "tinted"
+        }
+      ],
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "16x16"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "16x16"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "32x32"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "32x32"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "128x128"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "128x128"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "256x256"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "256x256"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "512x512"
+    },
+    {
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "512x512"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Applications/LLMBasic/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -0,0 +1,108 @@
+// Copyright © 2025 Apple Inc.
+
+import MLXLLM
+import MLXLMCommon
+import SwiftUI
+
+/// which model to load
+private let modelConfiguration = LLMRegistry.gemma3_1B_qat_4bit
+
+/// instructions for the model (the system prompt)
+private let instructions =
+    """
+    You are a friendly and helpful chatbot.
+    """
+
+/// parameters controlling generation
+private let generateParameters = GenerateParameters(temperature: 0.5)
+
+/// Downloads and loads the weights for the model -- we have one of these in the process
+@MainActor @Observable public class ModelLoader {
+
+    enum State {
+        case idle
+        case loading(Task<ModelContainer, Error>)
+        case loaded(ModelContainer)
+    }
+
+    public var progress = 0.0
+    public var isLoaded: Bool {
+        switch state {
+        case .idle, .loading: false
+        case .loaded: true
+        }
+    }
+
+    private var state = State.idle
+
+    public func model() async throws -> ModelContainer {
+        switch self.state {
+        case .idle:
+            let task = Task {
+                // download and report progress
+                try await loadModelContainer(configuration: modelConfiguration) { value in
+                    Task { @MainActor in
+                        self.progress = value.fractionCompleted
+                    }
+                }
+            }
+            self.state = .loading(task)
+            let model = try await task.value
+
+            self.state = .loaded(model)
+            return model
+
+        case .loading(let task):
+            return try await task.value
+
+        case .loaded(let model):
+            return model
+        }
+    }
+}
+
+/// View model for the ChatSession
+@MainActor @Observable public class ChatModel {
+
+    private let session: ChatSession
+
+    /// back and forth conversation between the user and LLM
+    public var messages = [Chat.Message]()
+
+    private var task: Task<Void, Error>?
+    public var isBusy: Bool {
+        task != nil
+    }
+
+    public init(model: ModelContainer) {
+        self.session = ChatSession(
+            model,
+            instructions: instructions,
+            generateParameters: generateParameters)
+    }
+
+    public func cancel() {
+        task?.cancel()
+    }
+
+    public func respond(_ message: String) {
+        guard task == nil else { return }
+
+        self.messages.append(.init(role: .user, content: message))
+        self.messages.append(.init(role: .assistant, content: "..."))
+        let lastIndex = self.messages.count - 1
+
+        self.task = Task {
+            var first = true
+            for try await item in session.streamResponse(to: message) {
+                if first {
+                    self.messages[lastIndex].content = item
+                    first = false
+                } else {
+                    self.messages[lastIndex].content += item
+                }
+            }
+            self.task = nil
+        }
+    }
+}

…ns/VLMEval/Assets.xcassets/Contents.json …s/LLMBasic/Assets.xcassets/Contents.jsonApplications/VLMEval/Assets.xcassets/Contents.json renamed to Applications/LLMBasic/Assets.xcassets/Contents.json Applications/VLMEval/Assets.xcassets/Contents.json renamed to Applications/LLMBasic/Assets.xcassets/Contents.json

@@ -0,0 +1,82 @@
+// Copyright © 2025 Apple Inc.
+
+import MLXLMCommon
+import SwiftUI
+
+struct ContentView: View {
+
+    /// provided by the application
+    let loader: ModelLoader
+
+    /// once loaded this will hold the chat session
+    @State var session: ChatModel?
+    @State var error: String?
+
+    /// prompt for the LLM (text field)
+    @State var prompt = ""
+
+    @FocusState var promptFocused
+
+    var body: some View {
+        VStack {
+            if let error {
+                Text("Error: \(error)")
+
+            } else if !loader.isLoaded {
+                ProgressView("Loading", value: loader.progress, total: 1)
+
+            } else if let session {
+                // show the chat messages
+                ScrollView(.vertical) {
+                    ForEach(session.messages.enumerated(), id: \.offset) { _, message in
+                        let bold = message.role == .user
+
+                        HStack {
+                            Text(message.content)
+                                .bold(bold)
+                            Spacer()
+                        }
+                        .padding(.bottom, 4)
+                    }
+
+                    Spacer()
+
+                    if session.isBusy {
+                        // a stop button -- cmd-. to interrupt
+                        HStack {
+                            Button("Stop", action: { session.cancel() })
+                                .keyboardShortcut(".")
+                            Spacer()
+                        }
+                    } else {
+                        // message from the user -> LLM
+                        TextField("Prompt", text: $prompt)
+                            .onSubmit(respond)
+                            .focused($promptFocused)
+                            .onAppear {
+                                promptFocused = true
+                            }
+                    }
+                }
+                .defaultScrollAnchor(.bottom)
+            }
+        }
+        .padding()
+        .task {
+            do {
+                let model = try await loader.model()
+                self.session = ChatModel(model: model)
+            } catch {
+                self.error = error.localizedDescription
+            }
+        }
+        .onDisappear {
+            self.session?.cancel()
+        }
+    }
+
+    private func respond() {
+        session?.respond(prompt)
+        prompt = ""
+    }
+}

Applications/LLMBasic/ChatModel.swift

@@ -4,13 +4,5 @@
 <dict>
 	<key>com.apple.developer.kernel.increased-memory-limit</key>
 	<true/>
-	<key>com.apple.security.app-sandbox</key>
-	<true/>
-	<key>com.apple.security.device.usb</key>
-	<true/>
-	<key>com.apple.security.files.user-selected.read-only</key>
-	<true/>
-	<key>com.apple.security.network.client</key>
-	<true/>
 </dict>
 </plist>

Applications/LLMBasic/ContentView.swift

@@ -0,0 +1,22 @@
+// Copyright © 2025 Apple Inc.
+
+import MLX
+import MLXLLM
+import MLXLMCommon
+import SwiftUI
+
+@main
+struct LLMBasicApp: App {
+
+    init() {
+        Memory.cacheLimit = 20 * 1024 * 1024
+    }
+
+    @State var loader = ModelLoader()
+
+    var body: some Scene {
+        WindowGroup {
+            ContentView(loader: loader)
+        }
+    }
+}