我是iOS的新开发者，我是从Firebase崩溃分析中得到此错误的。谁能帮我为什么会出现此错误？
Crashed: com.apple.main-thread
0 People Time Tracking 0x100c5009c closure #1 in closure #1 in SelectJobScreen.getPreviousStatus() (SelectJobScreen.swift:798)
1 People Time Tracking 0x100cb2648 thunk for @escaping @callee_guaranteed () -> () (<compiler-generated>)
2 libdispatch.dylib 0x1e6993a38 _dispatch_call_block_and_release + 24
3 libdispatch.dylib 0x1e69947d4 _dispatch_client_callout + 16
4 libdispatch.dylib 0x1e6942004 _dispatch_main_queue_callback_4CF$VARIANT$mp + 1068
5 CoreFoundation 0x1e6ee4ec0 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12
6 CoreFoundation 0x1e6edfdf8 __CFRunLoopRun + 1924
7 CoreFoundation 0x1e6edf354 CFRunLoopRunSpecific + 436
8 GraphicsServices 0x1e90df79c GSEventRunModal + 104
9 UIKitCore 0x212cc5b68 UIApplicationMain + 212
10 People Time Tracking 0x100c1afcc main (TodoItem.swift:17)
11 libdyld.dylib 0x1e69a58e0 start + 4
几天以来，我一直在尝试找出可能导致此崩溃的原因，但一直无法复制。我在这里看不到任何隐式的拆包或可选内容，但是如果重要的话，sessionId是会话对象中的非可选值。
我使用的是Swift 4.1，当运行各种不同版本的iOS 10、11和12的iOS设备上发生崩溃时，该应用程序确实支持某些版本的iOS 9，但尚未报告（尽管可能无关紧要，因为该应用的iOS 9用户群很小）
getPreviousStatus() func getPreviousStatus() {
let connect = JsonManger()
let app = UIApplication.shared.delegate as! AppDelegate
let user:User = app.dataManager.gUser
if Reachability.isConnectedToNetwork() {
self.showHUD( msg: "Loading...." )
connect.getLogDetails(baseUrl: user.ClientWeb, email: user.EmailID, password: user.Password, brugerId: user.BrugerID, success: { (res) in
var indud = false
if ( res.object(forKey: "indud") != nil ){
indud = res.object(forKey: "indud") as! Bool
}
if indud {
var isTodo = false
if res.object(forKey: "isToDo") != nil {
isTodo = res.object(forKey: "isToDo") as! Bool
}
if isTodo {
var str = res.object(forKey: "JobId") as! String
let index = str.index(str.startIndex, offsetBy: 1)
str = str.substring(from: index)
let prjId = Int(str)!
let project = app.dataManager.gProject.getProject(id: prjId)
let todoId = res.object(forKey: "TodoId") as! String
let todo = app.dataManager.gTodo.getTodo(id: Int(todoId)!)
self.project = project
self.todoItem = todo
app.dataManager.isCheckedin = true
self.des = res.object(forKey: "JobDescription") as? String
let startTime = res.object(forKey: "Dato2") as! String
DispatchQueue.main.async {
let ud = UserDefaults.standard
ud.set(true, forKey: "isCheckedIn")
ud.set( 1, forKey:"type")
ud.set( self.project.ID!, forKey: "projectId" )
ud.set( self.todoItem.ID! , forKey: "todoId" )
// print(" todo data is : \(self.todoItem.ID!)")
ud.set( self.des, forKey: "des")
ud.set( startTime,forKey: "startTime")
ud.set( startTime, forKey: "checkInTime" )
ud.synchronize()
self.hideHUD()
self.performSegue(withIdentifier: "goStartTodoFromSelect", sender: nil )
}
} else {
var jobId = res.object(forKey: "JobId") as! String
jobId = jobId.replacingOccurrences(of: "P", with: "")
self.des = res.object(forKey: "JobDescription") as? String
let jobCode = app.dataManager.gJobCode.getJobCode(id: Int(jobId)! )
self.jobCodeItem = jobCode
// let chekinTime = res.object(forKey: "Dato2") as! String
let startTime = "2019-05-15T19:45:00"
DispatchQueue.main.async {
app.dataManager.isCheckedin = true
let ud = UserDefaults.standard
ud.set(true, forKey: "isCheckedIn")
ud.set( 0, forKey:"type")
ud.set( jobId, forKey: "jobId" )
ud.set( startTime,forKey: "startTime")
ud.set( startTime, forKey: "checkInTime" )
if res.object(forKey: "JobDescription") != nil {
self.des = res.object(forKey: "JobDescription") as? String
ud.set( self.des, forKey: "des")
}
ud.synchronize()
DispatchQueue.main.async {
self.hideHUD()
self.performSegue(withIdentifier: "goStartJob", sender: nil )
}
}
}
} else {
DispatchQueue.main.async {
self.hideHUD()
// self.popToRoot()
for controller in self.navigationController!.viewControllers as Array {
if controller.isKind(of: SelectJobScreen.self) {
self.navigationController!.popToViewController(controller, animated: true)
break
}
}
}
}
}) { (error) in
DispatchQueue.main.async {
self.hideHUD()
// self.popToRoot()
for controller in self.navigationController!.viewControllers as Array {
if controller.isKind(of: SelectJobScreen.self) {
self.navigationController!.popToViewController(controller, animated: true)
break
}
}
}
}
} else {
print("Record Not Found")
}
}
答案 0 :(得分：1)
在getPreviousStatus（）函数获取空值的同时，使用调试对其进行一次检查
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