fix(ios): keep RiveFile alive until decode* completes (#225) (#266)

Fixes #225.

The crash was a use-after-free: `RiveFile` deallocated while asset
downloads are in-flight, leaving `RiveFactory` with a dangling
`rive::Factory*` pointer. Concurrent downloads widened the timing
window, making it look like a threading race.

Fix: strong `self` capture in decode closures keeps `activeFileRef` (and
thus `RiveFile`/`RenderContext`) alive until decode completes. All
decode types use a background serial queue via a `decodeAndApply`
helper.

Also upgrades rive-ios from 6.18.2 to 6.20.4 (includes CDN
use-after-free fix from rive-app/rive-ios#449).

Verified with 320+ mount/unmount stress cycles without crash.

Author: mfazekas

example/ios/Podfile.lock

@@ -1357,7 +1357,7 @@ PODS:
     - React-jsiexecutor
     - React-RCTFBReactNativeSpec
     - ReactCommon/turbomodule/core
-  - react-native-safe-area-context (5.6.2):
+  - react-native-safe-area-context (5.7.0):
     - DoubleConversion
     - glog
     - hermes-engine
@@ -1372,8 +1372,8 @@ PODS:
     - React-hermes
     - React-ImageManager
     - React-jsi
-    - react-native-safe-area-context/common (= 5.6.2)
-    - react-native-safe-area-context/fabric (= 5.6.2)
+    - react-native-safe-area-context/common (= 5.7.0)
+    - react-native-safe-area-context/fabric (= 5.7.0)
     - React-NativeModulesApple
     - React-RCTFabric
     - React-renderercss
@@ -1383,7 +1383,7 @@ PODS:
     - ReactCommon/turbomodule/bridging
     - ReactCommon/turbomodule/core
     - Yoga
-  - react-native-safe-area-context/common (5.6.2):
+  - react-native-safe-area-context/common (5.7.0):
     - DoubleConversion
     - glog
     - hermes-engine
@@ -1407,7 +1407,7 @@ PODS:
     - ReactCommon/turbomodule/bridging
     - ReactCommon/turbomodule/core
     - Yoga
-  - react-native-safe-area-context/fabric (5.6.2):
+  - react-native-safe-area-context/fabric (5.7.0):
     - DoubleConversion
     - glog
     - hermes-engine
@@ -1754,7 +1754,7 @@ PODS:
     - React-logger (= 0.79.2)
     - React-perflogger (= 0.79.2)
     - React-utils (= 0.79.2)
-  - RiveRuntime (6.18.2)
+  - RiveRuntime (6.20.4)
   - RNCAsyncStorage (2.2.0):
     - DoubleConversion
     - glog
@@ -1904,7 +1904,7 @@ PODS:
     - ReactCommon/turbomodule/core
     - RNWorklets
     - Yoga
-  - RNRive (0.4.2):
+  - RNRive (0.4.7):
     - DoubleConversion
     - glog
     - hermes-engine
@@ -1928,7 +1928,7 @@ PODS:
     - ReactCodegen
     - ReactCommon/turbomodule/bridging
     - ReactCommon/turbomodule/core
-    - RiveRuntime (= 6.18.2)
+    - RiveRuntime (= 6.20.4)
     - Yoga
   - RNScreens (4.18.0):
     - DoubleConversion
@@ -2347,7 +2347,7 @@ SPEC CHECKSUMS:
   React-logger: 8edfcedc100544791cd82692ca5a574240a16219
   React-Mapbuffer: c3f4b608e4a59dd2f6a416ef4d47a14400194468
   React-microtasksnativemodule: 054f34e9b82f02bd40f09cebd4083828b5b2beb6
-  react-native-safe-area-context: 0b8555c40461feb7198e999912a3446602e7c601
+  react-native-safe-area-context: 26634d9b636a98ceee20cb6fa5dc946922f1e90f
   React-NativeModulesApple: 2c4377e139522c3d73f5df582e4f051a838ff25e
   React-oscompat: ef5df1c734f19b8003e149317d041b8ce1f7d29c
   React-perflogger: 9a151e0b4c933c9205fd648c246506a83f31395d
@@ -2379,12 +2379,12 @@ SPEC CHECKSUMS:
   ReactAppDependencyProvider: 04d5eb15eb46be6720e17a4a7fa92940a776e584
   ReactCodegen: c63eda03ba1d94353fb97b031fc84f75a0d125ba
   ReactCommon: 76d2dc87136d0a667678668b86f0fca0c16fdeb0
-  RiveRuntime: 55c7a7badd9a8389d20fc8a75b7c6accc851b69a
+  RiveRuntime: f99ddd1d4b6a420dea5943ff52502e8f92ae7a92
   RNCAsyncStorage: a1c8cc8a99c32de1244a9cf707bf9d83d0de0f71
   RNCPicker: 28c076ae12a1056269ec0305fe35fac3086c477d
   RNGestureHandler: 6b39f4e43e4b3a0fb86de9531d090ff205a011d5
   RNReanimated: 66b68ebe3baf7ec9e716bd059d700726f250d344
-  RNRive: c02b3545abcf477d074945c5103f9f4bc9d8d672
+  RNRive: 042cbd7de1e5dd7e11aac076ade185926717543b
   RNScreens: f38464ec1e83bda5820c3b05ccf4908e3841c5cc
   RNWorklets: b1faafefb82d9f29c4018404a0fb33974b494a7b
   SocketRocket: d4aabe649be1e368d1318fdf28a022d714d65748

ios/ReferencedAssetLoader.swift

@@ -11,6 +11,7 @@ func createAssetFileError(_ assetName: String) -> NitroRiveError {
 }
 
 final class ReferencedAssetLoader {
+  private static let decodeQueue = DispatchQueue(label: "com.rive.asset-decode")
   private var activeLoadCount = 0
   private var activeFileRef: RiveFile?
 
@@ -35,43 +36,49 @@ final class ReferencedAssetLoader {
     RCTLogError("\(error)")
   }
 
+  /// Decodes an asset on a background serial queue, then applies the result
+  /// on the main thread. The `[self]` capture keeps `activeFileRef` alive
+  /// until completion, preventing use-after-free on the factory.
+  private func decodeAndApply<T>(
+    decode: @escaping () -> T?,
+    apply: @escaping (T) -> Void,
+    completion: @escaping () -> Void
+  ) {
+    Self.decodeQueue.async { [self] in
+      let result = decode()
+      DispatchQueue.main.async {
+        if let result { apply(result) }
+        completion()
+        _ = self
+      }
+    }
+  }
+
   private func processAssetBytes(
     _ data: Data, asset: RiveFileAsset, factory: RiveFactory, completion: @escaping () -> Void
   ) {
-    if data.isEmpty == true {
+    if data.isEmpty {
       completion()
       return
     }
-    DispatchQueue.global(qos: .background).async {
-      switch asset {
-      case let imageAsset as RiveImageAsset:
-        let decodedImage = factory.decodeImage(data)
-        DispatchQueue.main.async {
-          imageAsset.renderImage(decodedImage)
-          completion()
-        }
-      case let fontAsset as RiveFontAsset:
-        let decodedFont = factory.decodeFont(data)
-        DispatchQueue.main.async {
-          fontAsset.font(decodedFont)
-          completion()
-        }
-      case let audioAsset as RiveAudioAsset:
-        guard let decodedAudio = factory.decodeAudio(data) else {
-          DispatchQueue.main.async {
-            completion()
-          }
-          return
-        }
-        DispatchQueue.main.async {
-          audioAsset.audio(decodedAudio)
-          completion()
-        }
-      default:
-        DispatchQueue.main.async {
-          completion()
-        }
-      }
+    switch asset {
+    case let imageAsset as RiveImageAsset:
+      decodeAndApply(
+        decode: { factory.decodeImage(data) },
+        apply: { imageAsset.renderImage($0) },
+        completion: completion)
+    case let fontAsset as RiveFontAsset:
+      decodeAndApply(
+        decode: { factory.decodeFont(data) },
+        apply: { fontAsset.font($0) },
+        completion: completion)
+    case let audioAsset as RiveAudioAsset:
+      decodeAndApply(
+        decode: { factory.decodeAudio(data) },
+        apply: { audioAsset.audio($0) },
+        completion: completion)
+    default:
+      completion()
     }
   }