<__NSArrayM: 0x60000327cff0> was mutated while being enumerated

[kennym]

NSGenericException *** Collection <__NSArrayM: 0x283821110> was mutated while being enumerated. 
    Frameworks/CoreFoundation.framework/CoreFoundation ___exceptionPreprocess
    /usr/lib/libobjc.A.dylib _objc_exception_throw
    Frameworks/CoreFoundation.framework/CoreFoundation ___NSFastEnumerationMutationHandler
    /Users/runner/runners/2.158.0/work/1/s/node_modules/react-native-iap-3.2.3/ios/RNIapIos.m:305:5 -[RNIapIos productsRequest:didReceiveResponse:]
    Frameworks/StoreKit.framework/StoreKit ___27-[SKProductsRequest _start]_block_invoke_2
    /usr/lib/system/libdispatch.dylib __dispatch_call_block_and_release
    /usr/lib/system/libdispatch.dylib __dispatch_client_callout
    /usr/lib/system/libdispatch.dylib __dispatch_queue_override_invoke
    /usr/lib/system/libdispatch.dylib __dispatch_root_queue_drain
    /usr/lib/system/libdispatch.dylib __dispatch_worker_thread2
    /usr/lib/system/libsystem_pthread.dylib __pthread_wqthread
    /usr/lib/system/libsystem_pthread.dylib _start_wqthread

We see several instances of this error occurring in the wild. It might be us calling getProducts more than once in rapid succession, but I wonder if there's some defensive coding we could put in place, to prevent this error?

Version of react-native-iap

4.2.0

Version of react-native

0.61.4

Platforms you faced the error (IOS or Android or both?)

iOS

Expected behavior

No error

Actual behavior

Race condition

Tested environment (Emulator? Real Device?)

Real device/Emulator

Steps to reproduce the behavior

Unkown

[hyochan]

Thanks for the issue. I hope we could have minimal reproduction.

[tom-gurney]

I've noticed the same issue but only in release iOS versions, I can't replicate it at all in debug with the IAP sandbox, it seems to happen randomly and doesn't consistently crash and it's not affecting every user.

@kennym are you calling getAvailablePurchases() at all? As that seems to be what is causing the crash for me.

@hyochan I think for me it happens when I check if the user has an active subscription using the snippet from this thread: #275 (comment)

(I'm currently running react-native-iap 4.0.7)

[vischnabel]

Hey guys, how are you? I'm also currently experiencing this issue in production and, given that I'm not an Objective-C developer, I tried to look into the code to see what's happening.

-(void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response {
    for (SKProduct* prod in response.products) {
        [self addProduct:prod];
    }
    NSMutableArray* items = [NSMutableArray array];
    
    for (SKProduct* product in validProducts) {
        [items addObject:[self getProductObject:product]];
    }
    
    [self resolvePromisesForKey:RCTKeyForInstance(request) value:items];
}

The issue happens at the line

for (SKProduct* product in validProducts) {

and for what I have read, it has to do with multiple threads accessing the validProducts array at the same time, maybe because the method is being called multiple times in succession or something like that. On Stack Overflow, people have given 2 different solutions:

• Use synchronised to ensure thread safety.
• Copy the validProducts array before using it.

Do you think this is correct? Sorry if I'm being completely wrong about it, and thanks in advance.

[Chandrakala-B]

I am also facing the same problem. Could anyone help me with this

[kasl]

In version react-native-iap@4.3.3 same issue. Occurs on various devices (iPhone 6S, X, 11 pro max, 7, 8 etc) and OS versions 13. *
@hyochan Are there any plans to fix this problem?

[partiellkorrekt]

@vischnabel I'm not an Objectice-C developer myself but I added @synchronized to every access to validProducts as you proposed in your answer. As far as I can tell, this fixes the problem for me.

I created the following pull-request: #957