MCP - iPlayground

Want LLMs to use your own tools to get things done?
Want LLMs to help you accelerate tedious processes in development in the way you want?
Or are you looking at the dazzling array of MCP services on GitHub, wanting to download them but worried about hidden security risks or data-stealing logic? Then it's time to write your own.

This sharing will take you through understanding what the Model Context Protocol (MCP) defines and how it works from an iOS engineer's perspective.
We'll demonstrate with simple examples how to build your own MCP Tool, allowing AI assistants like Cursor and Windsurf to directly communicate with your own tools, eliminating the need to manually copy and paste your API results to AI.
Welcome all friends interested in automation, AI collaboration, and Swift implementation to join the discussion.

Transcript

1. 以iOS 工 程師 角 度所理解的MCP Chiaote Ni PicCollage & iOS@Taipei
2. 我今天是來推銷的😎
6. 1. A basic understanding of what MCP is and what it can do for you. 2. Practical knowledge of how could we implement our own MCP tools. After this session, you’ll walk away with:
7. Agenda MCP Basics - What is MCP? - Why and when do we need it? Building with Swift - How to write an MCP Server in Swift Making Life Easier - Some ways to simplify development
8. What is MCP?
9. • MCP（Model Context Protocol） • MCP is a protocol for model-context interaction. • It de fi nes how the client and server exchange information ex: capabilities, tools, and resources. Help the LLM understand how to use your tool !
10. 為什麼要讓AI看懂我們 工 具怎麼 用 ？
18. Why do we need to learn this protocol? Why do we need to make our own MCP server?
19. Security issue 🥷
20. • We will grant it permissions during setup • permissions to access and operate on fi les • permissions to access the internet • But you can’t be sure whether the tool has any hidden logic that secretly scrapes your data.
21. Save Our Clock-Out Time
22. Agent能 力 越強 就能幫我們做越多 工 作
23. 把 自己 的 工 作請同事幫忙 人 情是要還的
24. 但丟給AI不 用
25. 🎉
28. This is a JSON structure of a template 😱
31. When do we need to make our own MCP server: • Custom workflows • Workflows not yet supported by the official MCP Server • Templates or document repositories tailored to personal habits • Workflows with potential security concerns
32. MCP Basics
33. •MCP Hosts: ◦The AI application that coordinates and manages one or multiple MCP clients ◦Programs like Claude Desktop, IDEs, or AI tools that want to access data 
 through MCP •MCP Clients: ◦A component that maintains a connection to an MCP server and obtains context from an MCP server for the MCP host to use. •MCP Server: ◦A program that provides context to MCP clients
34. Claude Code Github MCP Server Template MCP Server Figma MCP Server MCP Client 1 MCP Client 2 MCP Client 3
35. Features • Servers o ff er any of the following features to clients. • Tools: Functions for the AI model to execute • Prompts: Templated messages and work fl ows for users • Resources: Context and data, for the user or the AI model to use • Clients may o ff er the following feature to servers. • Sampling: Server-initiated agentic behaviors and recursive LLM interactions
36. get_code_di f Tools MCP Client 1 Claude Code PR MCP Server Tool get_code_di f
37. get_template_pr_title Tools MCP Client 1 Claude Code PR MCP Server Tool get_code_di f Tool get_template
38. get_template_pr_description Tools MCP Client 1 Claude Code PR MCP Server Tool get_code_di f Tool get_template Tool get_template
39. MCP Client 1 create_pr Tools Claude Code PR MCP Server Tool get_code_di f Tool get_template Tool get_template Tool create_pr
40. Claude Code PR MCP Server MCP Client 1 create_pr Tools + Sampling Tool - create_pr
41. Claude Code PR MCP Server MCP Client 1 create_pr Tools + Sampling Tool - create_pr code di f
42. Claude Code PR MCP Server MCP Client 1 create_pr Tools + Sampling Tool - create_pr templates for PR title & description code di f
43. Claude Code PR MCP Server MCP Client 1 create_pr Tools + Sampling Tool - create_pr Ask the LLM to generate the PR details templates for PR title & description code di f
44. Claude Code PR MCP Server MCP Client 1 create_pr Tools + Sampling Tool - create_pr Sampling generate PR title & description Ask the LLM to generate the PR details templates for PR title & description code di f
45. Claude Code PR MCP Server MCP Client 1 create_pr Tools + Sampling Tool - create_pr Sampling generate PR title & description Ask the LLM to generate the PR details templates for PR title & description code di f create PR
46. Claude Code PR MCP Server MCP Client 1 create_pr Tools + Sampling Tool - create_pr Sampling generate PR title & description Ask the LLM to generate the PR details PR created successfully templates for PR title & description code di f create PR
47. Connection Methods • stdio - standard input/output for a local process • Streamable HTTP - server side event • Others Base Protocol • JSON-RPC message format • Stateful connections • Server and client capability negotiation Server Client Server Client 初始化能⼒交換 ⼯具與資源列舉 ⼯具執⾏與回傳 流程結束 Capability Initialization Request 1 Return Supported Capabilities 2 listTools listResources listPrompts 3 List Result Response 4 callTool (指定⼯具) 5 Tool Execution Result 6
48. How to use it How to make our own MCP server?
49. Community of fi cial swift-sdk 🎉🎉🎉
50. • Create a Swift package with an executable target swift package init --type executable --name MyMCPServer
51. • Create a Swift package with an executable target • Set up the dependency Package( name: "FormatMCPServer", platforms: [.macOS(.v13)], dependencies: [ .package( url: "https://github.com/modelcontextprotocol/swift-sdk.git", from: “0.9.0" ) ], targets: [ .executableTarget( name: "FormatMCPServer", dependencies: [.product(name: "MCP", package: "swift-sdk")], path: "Sources" ) ] ) swift package init --type executable --name MyMCPServer
53. • The fi le to be executed: • build.sh : #!/bin/bash cd "$(dirname "$0")" > /dev/null 2>&1 swift build -q -c release > /dev/null 2>&1 .build/arm64-apple-macosx/release/ProjectManagerMCPServer exit $? .build/arm64-apple-macosx/release/YOUR_PROJECT_NAME
54. { "mcpServers": { "project-manager": { "command": "sh", "args": [“/Users/aaron/DemoCode/MCPServer/ProjectManagerMCPServer/build.sh"], "description": "The MCP server supports project management blahblahblah” } } } 設定 :
55. Implementations
56. main.swift // 1. init the server let server = MCP.Server( name: "format-mcp-server", version: “1.0.0” )
57. main.swift // Declare the capabilities // supported by the server. capabilities: .init( logging: nil, prompts: nil, resources: nil, // listTool will only be called // by the client if tools are declared // in the capabilities. tools: .init(listChanged: true) Server Client Server Client 初始化能⼒交換 ⼯具與資源列舉 ⼯具執⾏與回傳 流程結束 Capability Initialization Request 1 Return Supported Capabilities 2 listTools listResources listPrompts 3 List Result Response 4 callTool (指定⼯具) 5 Tool Execution Result 6 let server = MCP.Server( name: "format-mcp-server", version: “1.0.0”, )
58. Server Client Server Client 初始化能⼒交換 ⼯具與資源列舉 ⼯具執⾏與回傳 流程結束 Capability Initialization Request 1 Return Supported Capabilities 2 listTools listResources listPrompts 3 List Result Response 4 callTool (指定⼯具) 5 Tool Execution Result 6 { "jsonrpc": "2.0", "id": 1, "method": "initialize", "params": { "protocolVersion": "2024-11-05", "capabilities": { "roots": { "listChanged": true }, "sampling": {}, "elicitation": {} }, "clientInfo": { "name": "ExampleClient", "title": "Example Client Display Name", "version": "1.0.0" } } } { "jsonrpc": "2.0", "id": 1, "method": "initialize", "params": { "protocolVersion": "2024-11-05", "capabilities": { "roots": { "listChanged": true }, "sampling": {}, "elicitation": {} }, "clientInfo": { "name": "ExampleClient", "title": "Example Client Display Name", "version": "1.0.0" } } }
59. Server Client Server Client 初始化能⼒交換 ⼯具與資源列舉 ⼯具執⾏與回傳 流程結束 Capability Initialization Request 1 Return Supported Capabilities 2 listTools listResources listPrompts 3 List Result Response 4 callTool (指定⼯具) 5 Tool Execution Result 6 { "jsonrpc": "2.0", "id": 1, "result": { "protocolVersion": "2024-11-05", "capabilities": { "logging": {}, "prompts": {}, "resources": { }, "tools": { "listChanged": true } }, "serverInfo": { "name": "ExampleServer", "title": "Example Server Display Name", "version": "1.0.0" } } }
60. Server Client Server Client 初始化能⼒交換 ⼯具與資源列舉 ⼯具執⾏與回傳 流程結束 Capability Initialization Request 1 Return Supported Capabilities 2 listTools listResources listPrompts 3 List Result Response 4 callTool (指定⼯具) 5 Tool Execution Result 6 ＯＫ，你有 支 援Tools 但不 支 援prompts & Resources 那我來跟你問全部Tools的介 面
61. Server Client Server Client 初始化能⼒交換 ⼯具與資源列舉 ⼯具執⾏與回傳 流程結束 Capability Initialization Request 1 Return Supported Capabilities 2 listTools listResources listPrompts 3 List Result Response 4 callTool (指定⼯具) 5 Tool Execution Result 6 // 2. Register the list of tools and their interfaces. await server.withMethodHandler(ListTools.self) { _ in return .init(tools: [ MCP.Tool.formatTemplateTool ]) }
62. Server Client Server Client 初始化能⼒交換 ⼯具與資源列舉 ⼯具執⾏與回傳 流程結束 Capability Initialization Request 1 Return Supported Capabilities 2 listTools listResources listPrompts 3 List Result Response 4 callTool (指定⼯具) 5 Tool Execution Result 6 // 3. Register the handler for tool invocation // (with manual parameter parsing). await server.withMethodHandler( CallTool.self ) { params in // Handle the params from tool call }
63. // 4. Start the server let transport = StdioTransport() try await server.start(transport: transport) await server.waitUntilCompleted()
64. 1. init the server 2. Register the list of tools and their interfaces. 3. Register the handler for call_tool 4. Start the server
65. Sounds easy, right?
66. Server Client Server Client 初始化能⼒交換 ⼯具與資源列舉 ⼯具執⾏與回傳 流程結束 Capability Initialization Request 1 Return Supported Capabilities 2 listTools listResources listPrompts 3 List Result Response 4 callTool (指定⼯具) 5 Tool Execution Result 6 // 2. Register the list of tools and their interfaces. await server.withMethodHandler(ListTools.self) { _ in return .init(tools: [ toolFormatTemplate, tool2, tool3, tool4 ]) }
67. Tool( name: "get_format_template", description: "Get format template for different types of content", inputSchema: .object([ "type": .string("object"), "properties": .object([ "formatType": .object([ "type": .string("string"), "description": .string("The type of format template to get"), "enum": .array([ .string("commit"), .string("pr-title"), .string("pr-description"), .string("branch"), .string("code-review") ]) ]) ]), "required": .array([.string("formatType")]) ]) )
68. Tool( name: "get_format_template", description: "Get format template for different types of content", inputSchema: .object([ "type": .string("object"), "properties": .object([ "formatType": .object([ "type": .string("string"), "description": .string("The type of format template to get"), "enum": .array([ .string("commit"), .string("pr-title"), .string("pr-description"), .string("branch"), .string("code-review") ]) ]) ]), "required": .array([.string("formatType")]) ]) ) { "tools": [ { "name": "get_format_template", "description": "Get format template... "inputSchema": { "type": "object", "properties": { "formatType": { "description": "The type of ... "enum": […], "type": "string" } }, "required": [ "formatType" ] } } ] }
69. Tool( name: "get_format_template", description: "Get format template for different types of content", inputSchema: .object([ "type": .string("object"), "properties": .object([ "formatType": .object([ "type": .string("string"), "description": .string("The type of format template to get"), "enum": .array([ .string("commit"), .string("pr-title"), .string("pr-description"), .string("branch"), .string("code-review") ]) ]) ]), "required": .array([.string("formatType")]) ]) ) "formatType": .object([ "description": .string("The type of format template to get"), "enum": .array([ .string("commit"), .string("pr-title"), .string("pr-description"), .string("branch"), .string("code-review") ]) ]) ])
70. Tool( name: "get_format_template", description: "Get format template for different types of content", inputSchema: .object([ "type": .string("object"), "properties": .object([ "formatType": .object([ "type": .string("string"), "description": .string("The type of format template to get"), "enum": .array([ .string("commit"), .string("pr-title"), .string("pr-description"), .string("branch"), .string("code-review") ]) ]) ]), "required": .array([.string("formatType")]) ]) ) .object([ "type": .string("object"), "properties": .object([ .object([ "type": .string("string"),
71. Server Client Server Client 初始化能⼒交換 ⼯具與資源列舉 ⼯具執⾏與回傳 流程結束 Capability Initialization Request 1 Return Supported Capabilities 2 listTools listResources listPrompts 3 List Result Response 4 callTool (指定⼯具) 5 Tool Execution Result 6 // 3. Register the handler for tool invocation // (with manual parameter parsing). await server.withMethodHandler( CallTool.self ) { params in // Handle the params from tool call }
72. switch params.name { case "get_format_template": guard let arguments = params.arguments else { return .init( content: [.text("Missing arguments")], isError: true ) } guard let formatTypeValue = arguments["formatType"]?.stringValue else { return .init( content: [.text("Missing required parameter: formatType")], isError: true ) } // Post-processing & return result default: return .init( content: [.text("Unknown tool: \(params.name)")], isError: true ) } switch params.name { case "get_format_template": let arguments = params.arguments guard let formatTypeValue = arguments["formatType"]?.stringValue else { return .init( content: [.text("Missing required parameter: formatType")], isError: true ) }
73. • Currently, there are only low-level APIs for those cases. • The SDK’s author hasn’t yet decided what its high-level API will look like. https://github.com/modelcontextprotocol/swift-sdk/issues/27
74. Tool( name: "get_format_template", description: "Get format template for different types of content", inputSchema: .object([ "type": .string("object"), "properties": .object([ "formatType": .object([ "type": .string("string"), "description": .string("The type of format template to get"), "enum": .array([ .string("commit"), .string("pr-title"), .string("pr-description"), .string("branch"), .string("code-review") ]) ]) ]), "required": .array([.string("formatType")]) ]) )
75. 不想努 力 了
76. What can we do for now?
77. Foundation Models
78. import FoundationModels @Generable struct FormatTemplateInput { @Guide(description: "The type of format template to get") var formatType: String } @Guide @Generable
79. @Guide @Generable
81. @Schema @Field
82. @Schema @Field( description: "The type of format template to get", constraint: .options([ "commit", "pr-title", "pr-description", "branch", "code-review" ]) ) • This is a marker-only attribute, used to indicate what should be generated for the property. • It doesn’t generate any implementation by itself, and must be used together with @Schema. • Generate the corresponding code based on the properties marked with @Field. @Field
84. @Schema struct FormatTemplateInput { @Field(description: "The type of format template to get") var formatType: String }
85. public static func parseArguments(_ args: [String: MCP.Value]) -> Self? { /* Tool call parsing */ } public static var inputSchema: MCP.Value { /* JSON Schema */ }
86. extension FormatTemplateInput: MCP.MCPParameterParsable { public static var inputSchema: MCP.Value { /* JSON Schema */ } public static func parseArguments(_ args: [String: MCP.Value]) -> Self? { /* Tool call parsing */ } } public static func parseArguments(_ args: [String: MCP.Value]) -> Self? { /* Tool call parsing */ } public static var inputSchema: MCP.Value { /* JSON Schema */ } @Schema struct FormatTemplateInput { @Field(description: "The type of format template to get") var formatType: String }
87. extension CallTool.Parameters { public func parseAs<T: MCPParameterParsable>(_ type: T.Type) -> T? { return T.parseArguments(self.arguments ?? [:]) } } extension FormatTemplateInput: MCP.MCPParameterParsable { public static var inputSchema: MCP.Value { /* JSON Schema */ } public static func parseArguments(_ args: [String: MCP.Value]) -> Self? { /* Tool call parsing */ } } public static func parseArguments(_ args: [String: MCP.Value]) -> Self? { /* Tool call parsing */ } public static var inputSchema: MCP.Value { /* JSON Schema */ }
88. await server.withMethodHandler(ListTools.self) { _ in .init(tools: [ Tool( name: "get_project_structure", description: "Get the complete three-level nested structure of a project", inputSchema: .object([ "type": .string("object"), "properties": .object([ "projectName": .object([ "type": .string("string"), "description": .string("Project name to retrieve") ]), "includeCompletedTasks": .object([ "type": .string("boolean"), "description": .string("Whether to include completed tasks"), "default": .bool(true) ]) ]), "required": .array([.string("projectName")]) ]) ), ]) }
89. await server.withMethodHandler(ListTools.self) { _ in .init(tools: [ Tool( name: "get_project_structure", description: "Get the complete three-level nested structure of a project", inputSchema: GetProjectStructureInput.inputSchema ) ]) } @Schema struct GetProjectStructureInput { @Field(description: "Project name to retrieve") let projectName: String @Field(description: "Whether to include completed tasks") let includeCompletedTasks: Bool? }
90. await server.withMethodHandler(CallTool.self) { params in switch params.name { case “get_project_structure": guard let args = params.arguments, let projectNameValue = args["projectName"], let projectName = projectNameValue.stringValue else { return .init( content: [.text("Invalid parameters for get_project_structure")], isError: true ) } let includeCompleted = args["includeCompletedTasks"]?.boolValue ?? true //... return .init(content: [.text(result)], isError: false) //... } }
91. await server.withMethodHandler(CallTool.self) { params in switch params.name { case “get_project_structure": guard let input = params.parseAs(GetProjectStructureInput.self) else { return .init( content: [.text("Invalid parameters for get_project_structure")], isError: true ) } let includeCompleted = input.includeCompletedTasks ?? true //... return .init(content: [.text(result)], isError: false) //... } }
93. struct SchemaFieldInfo { let name: String let type: String let description: String? let isRequiredField: Bool let isOptionalType: Bool let constraint: FieldConstraintInfo? } Intermediate Model SwiftSyntax Parsing Code Generation inputSchema: MCP.Value parseArguments(_:) • Parse @Field attributes • Parse the type of the property • Extract the property names • Detect @Field in nested types
94. struct SchemaFieldInfo { let name: String // inputSchema/parseArguments let type: String // inputSchema/parseArguments let description: String? // inputSchema let isRequiredField: Bool // inputSchema/parseArguments let isOptionalType: Bool // parseArguments let constraint: FieldConstraintInfo? // inputSchema }
95. @Schema struct FormatTemplateInput { @Field( description: "The type of format template to get”, constraint: .options( [ "commit", "pr-title", "pr-description", "branch", "code-review" ] ) ) var formatType: String } constraint: .options( [ "commit", "pr-title", "pr-description", "branch", "code-review" ] )
96. constraint: .options( [ "commit", "pr-title", "pr-description", "branch", "code-review" ] ) Constraint → JSON Schema - .options → "enum" - .range Int/Double → "minimum" / “maximum" String → "minLength" / “maxLength” Array → "minItems" / “maxItems”
97. @Schema struct CreateProjectInput { @Field(description: "Name of the project") let projectName: String @Field(description: "Project description") let description: String @Field(description: "Initial modules configuration") let modules: [ModuleInput]? } @Schema struct ModuleInput { @Field(description: "Module name") let name: String @Field(description: "Module description") let description: String @Field(description: "Initial tasks for this module") let tasks: [TaskInput]? } @Schema struct CreateProjectInput { @Field(description: "Initial modules configuration") let modules: [ModuleInput]? } @Schema struct ModuleInput { }
98. @Schema struct CreateProjectInput { //... @Field(description: "Initial modules configuration") let modules: [ModuleInput]? } extension CreateProjectInput: MCP.MCPParameterParsable { public static var inputSchema: MCP.Value { .object([ "type": .string("object"), "properties": .object([ //... "modules": .object([ "type": .string("array"), "items": ModuleInput.inputSchema, "description": .string("Initial modules configuration") ]) ]), //... ]) } extension CreateProjectInput: MCP.MCPParameterParsable { public static var inputSchema: MCP.Value { .object([ "modules": "items": ModuleInput.inputSchema, ]) //... ]) } }
99. How to debug our MCP server?
100. • Inspector: • https://github.com/modelcontextprotocol/inspector • npx @modelcontextprotocol/inspector • npx @modelcontextprotocol/inspector YOUR_SCRIPT • Cursor: • “Output” panel -> MCP Logs / A specific MCP Server
106. Conclusion
107. • MCP’s core idea includes its roles and key interactions. • Custom work fl ows or work fl ows needing security are good cases for building your own MCP server. • There’s now an of fi cial Swift SDK and debugging tool for building MCP servers.
 • Even though only low-level APIs are available, we can simplify the work using Swift Macros—just like FoundationModels does. Conclusion
108. swift-sdk:
 https://github.com/modelcontextprotocol/swift-sdk Provide high-level interface to Server
 https://github.com/modelcontextprotocol/swift-sdk/issues/27 Inspector
 https://github.com/modelcontextprotocol/inspector Model Context Protocol
 https://modelcontextprotocol.io/docs/getting-started/intro Reference swift-sdk (fork) - Swift Macro Interface - branch: feat/input-schema-macro
 https://github.com/ChiaoteNi/swift-sdk
109. 為什麼我們要學MCP 辛苦寫 工 具，來擴增AI的能 力 呢？
110. 因為我們不能將討厭的 工 作 直接丟包給其他 人
111. 但是丟包給AI
112. 可以
113. 🎉
114. 270,000,000 people around the world have downloaded our main PicCollage app.
115. Our new Products… Our new Products…
118. 一 般活動時間： 每 月 第 一 個週 二 pm: 21:30 ~ 10:00 下次活動時間：10 / 7 (以FB公告 & KK-ticket時間為準) FB GitHub KK-ticket
119. Thanks for your attention