Add support for NIP-36 Sensitive Content / Content Warning (#196)

README.md

@@ -44,7 +44,7 @@ The following [NIPs](https://github.com/nostr-protocol/nips) are implemented:
 - [x] [NIP-32: Labeling](https://github.com/nostr-protocol/nips/blob/master/32.md)
 - [ ] [NIP-34: `git` stuff](https://github.com/nostr-protocol/nips/blob/master/34.md)
 - [ ] [NIP-35: Torrents](https://github.com/nostr-protocol/nips/blob/master/35.md)
-- [ ] [NIP-36: Sensitive Content](https://github.com/nostr-protocol/nips/blob/master/36.md)
+- [x] [NIP-36: Sensitive Content](https://github.com/nostr-protocol/nips/blob/master/36.md)
 - [ ] [NIP-38: User Statuses](https://github.com/nostr-protocol/nips/blob/master/38.md)
 - [ ] [NIP-39: External Identities in Profiles](https://github.com/nostr-protocol/nips/blob/master/39.md)
 - [x] [NIP-40: Expiration Timestamp](https://github.com/nostr-protocol/nips/blob/master/40.md)

Sources/NostrSDK/Events/NostrEvent.swift

@@ -10,7 +10,7 @@ import Foundation
 /// A structure that describes a Nostr event.
 ///
 /// > Note: [NIP-01 Specification](https://github.com/nostr-protocol/nips/blob/master/01.md#events-and-signatures)
-public class NostrEvent: Codable, Equatable, Hashable, LabelTagInterpreting {
+public class NostrEvent: Codable, Equatable, Hashable, ContentWarningTagInterpreting, LabelTagInterpreting {
     public static func == (lhs: NostrEvent, rhs: NostrEvent) -> Bool {
         lhs.id == rhs.id &&
         lhs.pubkey == rhs.pubkey &&
@@ -318,7 +318,7 @@ public protocol NostrEventBuilding {
 
 public extension NostrEvent {
     /// Builder of a ``NostrEvent`` of type `T`.
-    class Builder<T: NostrEvent>: NostrEventBuilding, LabelBuilding {
+    class Builder<T: NostrEvent>: NostrEventBuilding, ContentWarningTagBuilding, LabelBuilding {
         public typealias EventType = T
 
         /// The event kind.

Sources/NostrSDK/Events/Tags/ContentWarningTag.swift

@@ -0,0 +1,31 @@
+//
+//  ContentWarningTag.swift
+//  NostrSDK
+//
+//  Created by Terry Yiu on 11/3/24.
+//
+
+import Foundation
+
+/// Interprets the content-warning tag.
+///
+/// See [NIP-36 Sensitive Content / Content Warning](https://github.com/nostr-protocol/nips/blob/master/36.md).
+public protocol ContentWarningTagInterpreting: NostrEvent {}
+public extension ContentWarningTagInterpreting {
+    /// Content warning to indicate that the event's content needs to be approved by readers to be shown. Clients can hide the content until the user acts on it.
+    var contentWarning: String? {
+        firstValueForRawTagName("content-warning")
+    }
+}
+
+/// Builder that adds a content warning to an event.
+///
+/// See [NIP-36 Sensitive Content / Content Warning](https://github.com/nostr-protocol/nips/blob/master/36.md).
+public protocol ContentWarningTagBuilding: NostrEventBuilding {}
+public extension ContentWarningTagBuilding {
+    /// Adds a content warning to indicate that the event's content needs to be approved by readers to be shown. Clients can hide the content until the user acts on it.
+    @discardableResult
+    func contentWarning(_ contentWarning: String) -> Self {
+        appendTags(Tag(name: "content-warning", value: contentWarning))
+    }
+}

Tests/NostrSDKTests/Events/Tags/ContentWarningTagTests.swift

@@ -0,0 +1,29 @@
+//
+//  ContentWarningTagTests.swift
+//  NostrSDK
+//
+//  Created by Terry Yiu on 11/3/24.
+//
+
+@testable import NostrSDK
+import XCTest
+
+final class ContentWarningTagTests: XCTestCase, EventVerifying {
+
+    func testCreateContentWarningTaggedEvent() throws {
+        let event = try NostrEvent.Builder(kind: .textNote)
+            .contentWarning("Trigger warning.")
+            .content("Pineapple goes great on pizza.")
+            .build(signedBy: .test)
+
+        XCTAssertEqual(event.contentWarning, "Trigger warning.")
+
+        XCTAssertEqual(event.tags.count, 1)
+        let tag = try XCTUnwrap(event.tags.first)
+        XCTAssertEqual(tag.name, "content-warning")
+        XCTAssertEqual(tag.value, "Trigger warning.")
+
+        try verifyEvent(event)
+    }
+
+}