Crashed: com.apple.main-thread partial apply for closure #2 - ios

Question

Crashes are reported into firebase console. Can anyone help me. i am sending data to server using Socket.
Here is crash description:
Crashed: com.apple.main-thread
0 AppName 0x10ef40 partial apply for closure #2 in sendDataRecursively() + 4329697088 (swift:4329697088)
1 AppName 0x23824 thunk for #escaping #callee_guaranteed () -> () + 4328732708 (<compiler-generated>:4328732708)
2 libdispatch.dylib 0x1e68 _dispatch_call_block_and_release + 32
3 libdispatch.dylib 0x3a2c _dispatch_client_callout + 20
4 libdispatch.dylib 0x11f48 _dispatch_main_queue_drain + 928
5 libdispatch.dylib 0x11b98 _dispatch_main_queue_callback_4CF + 44
6 CoreFoundation 0x522f0
CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 16
7 CoreFoundation 0xc1f4 __CFRunLoopRun + 2532
8 CoreFoundation 0x1f6b8 CFRunLoopRunSpecific + 600
9 GraphicsServices 0x1374 GSEventRunModal + 164
10 UIKitCore 0x513e88 -[UIApplication _run] + 1100
11 UIKitCore 0x2955ec UIApplicationMain + 364
12 AppName 0x48dac main + 17 (AppDelegate.swift:17)
13 ??? 0x1008edce4 (Missing)
Here is my function:
#objc func sendDataRecursively() {
let reachability = try! Reachability()
if reachability.connection != .unavailable {
DispatchQueue.global(qos: .userInitiated).async { //previous .bakground
if self.msgCnt == 127 {
self.msgCnt = 0
}
self.msgCnt += 1
self.sendRequest()
}
} else {
DispatchQueue.main.async {
self.previousStatusWhenDisconnect = self.motionDetectionLbl?.text ?? ""
self.appDelegate.statusLbl?.text = String(format: "%# %#", (self.appDelegate.statusLbl?.text)!, StartVCStringsEnglish.disConnectedString)
}
self.networkTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.checkNetworkRecursively), userInfo: nil, repeats: true)
}
}
Here is the my other function. i am sending data to my Socket function. i did't got the crash but its reported into firebase. Also in firebase has not much more information about the crash. its just show the function name only.
private func sendRequest() {
self.calculateMessageData()
var requestData: Data?
var txData = [UInt8()]
var crc: Int
if self.msgID == Int8(EnMessageType.basicSafetyMessage.rawValue) {
requestData = self.getBasicSafetyMessage()
} else {
requestData = self.getPersonalSafetyMessage()
}
crc = computeCRC(data: requestData!, length: requestData!.count)
// wrap data in 7E, do byte stuffing and add CRC
txData = []
txData.append(0x7E)
for ii in 0..<requestData!.count {
switch requestData![ii] {
case 0x7D:
txData.append(0x7D)
txData.append(0x5D)
break
case 0x7E:
txData.append(0x7D)
txData.append(0x5E)
break
default:
txData.append(requestData![ii])
break
}
}
txData.append((UInt8)(crc >> 8))
txData.append((UInt8)(crc & 0xFF))
txData.append(0x7E)
requestData = (Data)(txData)
if AppSingletonVariable.sharedInstance.isConnected == true { AppSingletonVariable.sharedInstance.mySocket.sendDataToServer(reqData: requestData!)
}
}
Thanks,

Answer 1

You can see from the crash description that there is issue in 2nd closure in sendDataRecursively() function:
DispatchQueue.main.async {
self.previousStatusWhenDisconnect = self.motionDetectionLbl?.text ?? ""
self.appDelegate.statusLbl?.text = String(format: "%# %#", (self.appDelegate.statusLbl?.text)!, StartVCStringsEnglish.disConnectedString)
}
self.networkTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.checkNetworkRecursively), userInfo: nil, repeats: true)
The issue is probably '!' in this expression:
(self.appDelegate.statusLbl?.text)!
If statusLbl is nil, this code crashes. As it was mentioned in comment, it's not safe to force unwrap optionals and this is the reason.
Replace your closure with this:
DispatchQueue.main.async {
self.previousStatusWhenDisconnect = self.motionDetectionLbl?.text ?? ""
if let text = self.appDelegate.statusLbl?.text {
self.appDelegate.statusLbl?.text = String(format: "%# %#", text, StartVCStringsEnglish.disConnectedString)
}
}
self.networkTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.checkNetworkRecursively), userInfo: nil, repeats: true)