[iOS] FilePicker.saveFile() Hangs Without Opening File Dialog

[alexaungmyooo]

Describe the bug
The FilePicker.platform.saveFile() method hangs indefinitely on iOS and does not open the file save dialog. The issue occurs with the latest version of the file_picker plugin (8.1.4) even in the provided example app.

This happens consistently on both physical devices and simulators, with no meaningful error messages or logs indicating the cause.

Platform

• [ ] Android
• [✓] iOS
• [ ] Web
• [ ] Desktop

Platform OS version
iOS 18.0.1 (22A3370) (Observed on both simulator and physical devices)
Model: iPhone 15 Plus

How are you picking?

try {
  final result = await FilePicker.platform.saveFile(
    dialogTitle: 'Save Backup File',
    fileName: 'test_backup.zip',
  );

  if (result == null) {
    print('User canceled the picker.');
  } else {
    print('File saved at: $result');
  }
} catch (e) {
  print('Error: $e');
}

Details to reproduce the issue

- Clone the official file_picker GitHub repository and navigate to the example app.
- Run the example app on an iOS device or simulator.
- Tap the "Save File" button.
- Observe that the app hangs indefinitely, and no file dialog appears.

Error Log
No Flutter-side errors are reported, but the app hangs when FilePicker.platform.saveFile() is invoked.

But we got this error in xcode

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSNull data]: unrecognized selector sent to instance 0x1f67ef748'
*** First throw call stack:
(0x19187108c 0x18eb732e4 0x1919777c8 0x19180e888 0x19180e1b0 0x104fb5e14 0x104fb5aac 0x1084dacc4 0x107f5cd88 0x104aa8a30 0x104aaa71c 0x104abade8 0x104aba9a4 0x191843f64 0x191841188 0x1918405b8 0x1dd2d61c4 0x1943962c0 0x194444ddc 0x104e64124 0x1b7014d34)
libc++abi: terminating due to uncaught exception of type NSException

Screenshots and/or video
Not applicable since the dialog does not appear.

Flutter Version details

[✓] Flutter (Channel stable, 3.24.5, on macOS 15.1.1 24B91 darwin-x64, locale en-GB)
    • Flutter version 3.24.5 on channel stable at /Users/aungmyooo/Development/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision dec2ee5c1f (3 weeks ago), 2024-11-13 11:13:06 -0800
    • Engine revision a18df97ca5
    • Dart version 3.5.4
    • DevTools version 2.37.3

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/aungmyooo/Library/Android/sdk
    • Platform android-35, build-tools 34.0.0
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.11+0-17.0.11b1207.24-11852314)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 16.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 16B40
    • CocoaPods version 1.16.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2024.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.11+0-17.0.11b1207.24-11852314)

[✓] VS Code (version 1.95.3)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.102.0

[✓] Connected device (3 available)
    • Aung Myo’s iPhone (mobile) • 00008120-0006612E0198A01E • ios            • iOS 18.0.1 22A3370
    • macOS (desktop)            • macos                     • darwin-x64     • macOS 15.1.1 24B91 darwin-x64
    • Chrome (web)               • chrome                    • web-javascript • Google Chrome 131.0.6778.86

[✓] Network resources
    • All expected network resources are available.

• No issues found!

Additional context
The Info.plist includes all required keys:

<key>LSSupportsOpeningDocumentsInPlace</key>
<true/>
<key>UIFileSharingEnabled</key>
<true/>
<key>UISupportsDocumentBrowser</key>
<true/>
<key>UIBackgroundModes</key>
<array>
<string>fetch</string>
<string>remote-notification</string>
</array>

The Podfile configuration:

platform :ios, '13.0'

target 'Runner' do
  use_frameworks!
  use_modular_headers!

  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
end

[github-actions]

This issue is stale because it has been open for 7 days with no activity.