[iOS] NSInternalInconsistencyException Crash

[MPinto16]

Our app is experiencing a crash on iOS devices, which appears to be related to the flutter_eco_mode package. The crash occurs when data is being sent through a method channel, leading to an NSInternalInconsistencyException.

Crash Details

We cannot reproduce the issue directly, but it has been reported multiple times on Crashlytics with the following stack trace:

Fatal Exception: NSInternalInconsistencyException
0  CoreFoundation                 0x8408c __exceptionPreprocess
1  libobjc.A.dylib                0x172e4 objc_exception_throw
2  Foundation                     0x8222fc -[NSMutableDictionary(NSMutableDictionary) initWithContentsOfFile:]
3  Flutter                        0x5d9658 WriteValueOfType(void const*, __CFData*, FlutterStandardCodecObjcType, void const*) + 341 (FlutterStandardCodec.mm:341)
4  Flutter                        0x5d92e0 -[FlutterStandardWriter writeValue:] + 351 (FlutterStandardCodec.mm:351)
5  Flutter                        0x5da528 -[FlutterStandardMethodCodec encodeSuccessEnvelope:] + 95 (FlutterStandardCodec.mm:95)
6  Flutter                        0x5d5ef8 invocation function for block in SetStreamHandlerMessageHandlerOnChannel(NSObject<FlutterStreamHandler>*, NSString*, NSObject<FlutterBinaryMessenger>*, NSObject<FlutterMethodCodec>*, NSObject<FlutterTaskQueue>*) + 398 (FlutterChannels.mm:398)
7  flutter_eco_mode               0x4364 thunk for @escaping @callee_unowned @convention(block) (@unowned Swift.AnyObject?) -> () (<compiler-generated>)
8  flutter_eco_mode               0x4cb8 closure #1 in BatteryStateStreamHandler.batteryStateChanged(_:) + 196 (FlutterEcoModePlugin.swift:196)
9  flutter_eco_mode               0x4764 thunk for @escaping @callee_guaranteed () -> () (<compiler-generated>)
10 libdispatch.dylib              0x2370 _dispatch_call_block_and_release
11 libdispatch.dylib              0x40d0 _dispatch_client_callout
12 libdispatch.dylib              0x129e0 _dispatch_main_queue_drain
13 libdispatch.dylib              0x125fc _dispatch_main_queue_callback_4CF
14 CoreFoundation                 0x56f64 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__
15 CoreFoundation                 0x54188 __CFRunLoopRun
16 CoreFoundation                 0x535b8 CFRunLoopRunSpecific
17 GraphicsServices               0x11c4 GSEventRunModal
18 UIKitCore                      0x3de2c0 -[UIApplication _run]
19 UIKitCore                      0x48cddc UIApplicationMain
20 UIKitCore                      0x7b9b20 block_destroy_helper.23
21 Runner                         0x8aa0 main (AppDelegate.swift)
22 ???                            0x1bc5e0d34 (Manquant)
        

Additional Context

Flutter Version: 3.24.4
flutter_eco_mode Version: 0.0.3
iOS Version: The crash has been observed from iOS 16 until 18.1.0

[apoichet]

Hi MPinto16, thank you for sharing your crash with this issue.

Honestly, it's a curious crash and it's never happened for us.
Regarding your stack trace, it concerns an event channel in iOS native code to listen the battery state changes.

Be sure that if we reproduce something like this, we'll notice you directly in this thread.
We can keep this issue open during this time.

[githhhh]

Hi MPinto16, thank you for sharing your crash with this issue.

Honestly, it's a curious crash and it's never happened for us. Regarding your stack trace, it concerns an event channel in iOS native code to listen the battery state changes.

Be sure that if we reproduce something like this, we'll notice you directly in this thread. We can keep this issue open during this time.

@apoichet
I found a way to reproduce the issue. When the app is packaged as a test build and installed separately on the device, rather than running directly through debugging, the crash occurs.

To reproduce:

• Ensure the app is running.
• Plug in the charging cable.
• At the moment the charging state changes, the app crashes.

Below is the crash log:

Last Exception Backtrace:
0 CoreFoundation 0x19c1fc7cc __exceptionPreprocess + 164
1 libobjc.A.dylib 0x1994cf2e4 objc_exception_throw + 88
2 Foundation 0x19b5cca78 -[NSMutableDictionary(NSMutableDictionary) initWithContentsOfFile:] + 0
3 Flutter 0x1083ad258 0x107de8000 + 6050392
4 Flutter 0x1083acee0 0x107de8000 + 6049504
5 Flutter 0x1083ae128 0x107de8000 + 6054184
6 Flutter 0x1083a9b30 0x107de8000 + 6036272
7 flutter_eco_mode 0x1068e4380 thunk for @escaping @callee_unowned @convention(block) (@unowned Swift.AnyObject?) -> () + 192
8 flutter_eco_mode 0x1068e4ce0 closure #1 in BatteryStateStreamHandler.batteryStateChanged(_:) + 72
9 flutter_eco_mode 0x1068e4784 thunk for @escaping @callee_guaranteed () -> () + 28
10 libdispatch.dylib 0x1a3ed0370 _dispatch_call_block_and_release + 32
11 libdispatch.dylib 0x1a3ed20d0 _dispatch_client_callout + 20
12 libdispatch.dylib 0x1a3ee09e0 _dispatch_main_queue_drain + 980
13 libdispatch.dylib 0x1a3ee05fc _dispatch_main_queue_callback_4CF + 44
....

[githhhh]

The issue seems quite clear.
let batteryState = convertBatteryState(state: UIDevice.current.batteryState)
This function returns a Swift value, which is not a Flutter-compatible type.

Debugging Output:

(lldb) p type(of: batteryState)
(flutter_eco_mode.BatteryState.Type) flutter_eco_mode.BatteryState

(lldb) p batteryState
(flutter_eco_mode.BatteryState) charging

Since batteryState is an enum (flutter_eco_mode.BatteryState), Flutter fails to parse it, leading to a crash.