Xcode build running on device but failing on simultor - ios

Question

I'm using CocoaPods with a React Native app. I've had various errors when running builds in the Xcode simulator. I don't have issues running it on my device. Here's one that I get when I have breakpoints enabled:
- (void)ensureOnJavaScriptThread:(dispatch_block_t)block
{
RCTAssert(_jsThread, #"This method must not be called before the JS thread is created");
The error here is green (yet breaking, thanks Xcode) and it says com.facebook.react.JavaScript (9): breakpoint 1.2
I get two errors when I disable breakpoints, this is one:
void Instance::loadApplication(std::unique_ptr<RAMBundleRegistry> bundleRegistry,
std::unique_ptr<const JSBigString> string,
std::string sourceURL) {
callback_->incrementPendingJSCalls();
SystraceSection s("Instance::loadApplication", "sourceURL",
sourceURL);
nativeToJsBridge_->loadApplication(std::move(bundleRegistry), std::move(string),
std::move(sourceURL));
}
with the red error on the callback_-> line reading EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
the second is this a signal SIGABRT error from this code:
int main(int argc, char * argv[]) {
#autoreleasepool {
return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
}
}
I think i've fixed that issue before by enabling zombies. When I do that, I see this in the console:
2018-07-11 16:56:08.326 [info][tid:main][RCTRootView.m:293] Running application Mapp ({
initialProps = {
};
rootTag = 11;
})
=================================================================
Main Thread Checker: UI API called on a background thread: -[UIApplication setNetworkActivityIndicatorVisible:]
PID: 34682, TID: 5546845, Thread name: (none), Queue name: com.mixpanel.20e6d2c2b6c431dfecfdfaa100ec0a11.0x7fa94db06940.network, QoS: 0
Backtrace:
4 Mapp 0x0000000103a31dd9 -[MPNetwork updateNetworkActivityIndicator:] + 121
5 Mapp 0x0000000103a2ec09 -[MPNetwork flushQueue:endpoint:] + 985
6 Mapp 0x0000000103a2e7b0 -[MPNetwork flushEventQueue:] + 64
7 Mapp 0x0000000103a10418 __32-[Mixpanel flushWithCompletion:]_block_invoke + 312
8 libdispatch.dylib 0x000000010e3f47ab _dispatch_call_block_and_release + 12
9 libdispatch.dylib 0x000000010e3f57ec _dispatch_client_callout + 8
10 libdispatch.dylib 0x000000010e3fdbe5 _dispatch_queue_serial_drain + 1305
11 libdispatch.dylib 0x000000010e3fe4fa _dispatch_queue_invoke + 328
12 libdispatch.dylib 0x000000010e3fa344 _dispatch_queue_override_invoke + 726
13 libdispatch.dylib 0x000000010e40136c _dispatch_root_queue_drain + 664
14 libdispatch.dylib 0x000000010e401076 _dispatch_worker_thread3 + 132
15 libsystem_pthread.dylib 0x000000010e920169 _pthread_wqthread + 1387
16 libsystem_pthread.dylib 0x000000010e91fbe9 start_wqthread + 13
This to me is unreadable. I don't understand what's wrong. Reminder: this build runs without breaking errors on my device, even when breakpoints are enabled. Is this something I should worry about? Please help!

Answer 1

Because in your code UI API called on a background thread. So please disable the Main Thread Checker of xcode. it will work.
Edit Scheme --- > Diagonstics --- > Runtime API Checking ---> Main
Thread Checker (un-check this setting)
Note: Always update the UI inside below method on a background thread
Or
Put your [UIApplication setNetworkActivityIndicatorVisible:] Method inside DispatchQueue.main.async
DispatchQueue.main.async { // Correct
UIApplication.shared.isNetworkActivityIndicatorVisible = true // in swift 4
[UIApplication setNetworkActivityIndicatorVisible:]// in objective-C
}
https://developer.apple.com/documentation/code_diagnostics/main_thread_checker