🐞 Bug Report: BackgroundTimer.setInterval not working on iOS

[quangtuan28200]

Here is my react native info:

System:
OS: macOS 26.1
CPU: (10) arm64 Apple M4
Memory: 126.67 MB / 16.00 GB
Shell:
version: "5.9"
path: /bin/zsh
Binaries:
Node:
version: 22.21.1
path: ~/.nvm/versions/node/v22.21.1/bin/node
Yarn:
version: 3.6.4
path: /opt/homebrew/bin/yarn
npm:
version: 10.9.4
path: ~/.nvm/versions/node/v22.21.1/bin/npm
Watchman:
version: 2025.03.03.00
path: /opt/homebrew/bin/watchman
Managers:
CocoaPods:
version: 1.16.2
path: /Users/tian/.rbenv/shims/pod
SDKs:
iOS SDK:
Platforms:
- DriverKit 24.5
- iOS 18.5
- macOS 15.5
- tvOS 18.5
- visionOS 2.5
- watchOS 11.5
Android SDK:
API Levels:
- "34"
- "35"
- "36"
Build Tools:
- 35.0.0
- 36.0.0
System Images:
- android-34 | Google Play ARM 64 v8a
- android-35 | Google Play ARM 64 v8a
- android-35 | Pre-Release 16 KB Page Size Google Play ARM 64 v8a
Android NDK: Not Found
IDEs:
Android Studio: 2025.1 AI-251.26094.121.2512.13840223
Xcode:
version: 16.4/16F6
path: /usr/bin/xcodebuild
Languages:
Java:
version: 17.0.16
path: /opt/homebrew/opt/openjdk@17/bin/javac
Ruby:
version: 3.2.2
path: /Users/tian/.rbenv/shims/ruby
npmPackages:
"@react-native-community/cli":
installed: 20.0.0
wanted: 20.0.0
react:
installed: 19.1.1
wanted: 19.1.1
react-native:
installed: 0.82.1
wanted: 0.82.1
react-native-macos: Not Found
npmGlobalPackages:
"react-native": Not Found
Android:
hermesEnabled: true
newArchEnabled: true
iOS:
hermesEnabled: true
newArchEnabled: true

[ddeschenes-gaiia]

Same. Using Expo SDK 54 with RN 81. Tried on real device. Works great on android. Added app.config.ts config:

Wonder why clearInterval is called after setInterval. I commented the code and it worked properly in ios physical device. Looks like the interval is clear before running.

@tconns

[jacksonknightwood]

+1 Same issue.
Timer not working on iOS.

[ddeschenes-gaiia]

I tried to contribute and create a PR that fixes it but I am rejected and the Github settings does not allow to create PR. Here is a patch file (using patch-package) that fixes it.

Issue is that it seems to clear the timer before initializing it (since in a separated async thread)

diff --git a/node_modules/react-native-nitro-bg-timer/ios/NitroBackgroundTimer.swift b/node_modules/react-native-nitro-bg-timer/ios/NitroBackgroundTimer.swift
index 560545b..ab2eb11 100644
--- a/node_modules/react-native-nitro-bg-timer/ios/NitroBackgroundTimer.swift
+++ b/node_modules/react-native-nitro-bg-timer/ios/NitroBackgroundTimer.swift
@@ -51,7 +51,9 @@ class NitroBackgroundTimer: HybridNitroBackgroundTimerSpec {
       
       DispatchQueue.main.async {
         // Clear existing timer with same ID
-        self.clearTimeout(id: id)
+        if (self.timeoutTimers[intId] != nil){
+          self.clearTimeout(id: id)
+        }
         self.acquireBackgroundTask()
 
         let timer = Timer.scheduledTimer(withTimeInterval: duration / 1000.0, repeats: false) { [weak self] _ in
@@ -101,7 +103,10 @@ class NitroBackgroundTimer: HybridNitroBackgroundTimerSpec {
       
       DispatchQueue.main.async {
         // Clear existing timer with same ID
-        self.clearInterval(id: id)
+        if (self.intervalTimers[intId] != nil){
+          self.clearInterval(id: id)
+        }
+    
         self.acquireBackgroundTask()
 
         let timer = Timer.scheduledTimer(withTimeInterval: interval / 1000.0, repeats: true) { [weak self] _ in