核心位置为ObservableObject的SwiftUI崩溃 [英] SwiftUI with Core Location as ObservableObject crashes
问题描述
我正在尝试使用Core Location获取CLRegionState来更新SwiftUI应用程序中的元素。我正在使用XCode 11 beta 6，并且在我的设备上安装了iOS 13 beta 7。
I am trying to use Core Location to get the CLRegionState to update elements in a SwiftUI app. I am using XCode 11 beta 6 and have iOS 13 beta 7 on my device.
我可以看到两个问题：
-
应用程序崩溃并显示错误线程1：第147行出现EXC_BAD_ACCESS（... ScrollView {...）
The app crashes and the error Thread 1: EXC_BAD_ACCESS appears on line 147 (...ScrollView {... )
CLRegionState永远不会被调用或不会更新。
The CLRegionState is never called or does not update.
我基于此Paul Hudson关于SwiftUI信标检测器的教程（我也无法使它工作）的一部分，并对其进行了修改以使用CLRegionState而不是信标接近度。
I am basing this off of Paul Hudson's tutorial on SwiftUI Beacon Detector (which I have not been able to make work either), and modifying it to use CLRegionState instead of beacon proximity .
这里是代码：
import SwiftUI
import CoreLocation
import Combine
class MYLocationManager: NSObject, ObservableObject, CLLocationManagerDelegate {
var locationManager: CLLocationManager?
var willChange = PassthroughSubject<Void, Never>()
var lastRegionState = CLRegionState.unknown
override init() {
super.init()
locationManager = CLLocationManager()
locationManager?.delegate = self
locationManager?.requestWhenInUseAuthorization()
}
func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
checkLocationAuthorization()
}
func update(state: CLRegionState) {
lastRegionState = state
willChange.send(())
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
guard let location = locations.last else { return }
print("Your location is \(location)")
update(state: .unknown)
}
func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
print(error)
}
func startScanning() {
// temporary coordinates
var workCoordinates: CLLocationCoordinate2D {
return CLLocationCoordinate2D(
latitude: 43.486525,
longitude: -11.912542)
}
var homeCoordinates = CLLocationCoordinate2D(
latitude: 43.499541,
longitude: -11.875079)
let workRegion: CLCircularRegion = CLCircularRegion(center: workCoordinates, radius: 100, identifier: "Work")
let homeRegion: CLCircularRegion = CLCircularRegion(center: homeCoordinates, radius: 100, identifier: "Home")
locationManager!.startMonitoring(for: workRegion)
locationManager!.startMonitoring(for: homeRegion)
locationManager!.requestState(for: workRegion)
locationManager!.requestState(for: homeRegion)
}
func locationManager(_ manager: CLLocationManager, didDetermineState state: CLRegionState, for region: CLRegion) {
switch state {
case .inside:
switch region.identifier {
case "Work":
print("You are at work")
case "Home":
print("You are at home")
default:
print("unknown")
}
default:
break
}
}
func locationManager(_ manager: CLLocationManager, didEnterRegion region: CLRegion) {
switch region.identifier {
case "Work":
print("Work**********")
//self.taskTypeSegCtrl.selectedSegmentIndex = 0
case "Home":
print("Home*********8")
//self.taskTypeSegCtrl.selectedSegmentIndex = 1
default:
break
}
}
func checkLocationAuthorization() {
switch CLLocationManager.authorizationStatus() {
case .authorizedWhenInUse:
startScanning()
break
case .authorizedAlways:
startScanning()
break
case .denied:
// show an alert instructing them howto turn on permissions
break
case .notDetermined:
print("Location authorization is not determined.")
locationManager!.requestAlwaysAuthorization()
break
case .restricted:
break
@unknown default:
fatalError()
}
}
}
struct ContentView: View {
@Environment(\.managedObjectContext) var managedObjectContext
@FetchRequest(entity: Task.entity(),
sortDescriptors: [NSSortDescriptor(
keyPath: \Task.name, ascending: true)])
var tasks: FetchedResults<Task>
var locationManager = CLLocationManager()
@ObservedObject var location: MYLocationManager = MYLocationManager()
@State private var taskName = ""
@State private var taskType = 0
@State private var selectedTask = ""
@State private var numberOfTaps = 0
@State private var regionState = CLRegionState.unknown
var body: some View {
ScrollView {
VStack {
TextField("Enter a task name", text: $taskName)
.textFieldStyle(RoundedBorderTextFieldStyle())
Picker(selection: $taskType, label: Text("Task type")) {
Text("Work").tag(1)
Text("Home").tag(2)
}.pickerStyle(SegmentedPickerStyle())
Text(selectedTask)
Button(action: {
let task = Task(context: self.managedObjectContext)
task.name = self.taskName
task.type = Int16(self.taskType)
do {
try self.managedObjectContext.save()
} catch {
// handle the Core Data error
}
self.taskName = ""
}) {
Text("Save Task")
}.padding()
Button(action: {
if self.numberOfTaps < self.tasks.count {
let task = self.tasks[self.numberOfTaps].name
self.selectedTask = task ?? "No task..."
self.numberOfTaps = self.numberOfTaps + 1
} else {
self.selectedTask = "No more tasks! Have a wonderful day."
}
}) {
Text("Next Task")
}
List {
ForEach(tasks, id: \.self) {
task in
VStack(alignment: .leading, spacing: 6) {
Text(task.name ?? "Unknown")
.font(.headline)
Text("Task type \(task.type)")
.font(.caption)
}
}.onDelete(perform: removeTask)
}
} .frame(width: 300, height: 400, alignment: .top)
.padding()
.border(Color.black)
if regionState == .inside {
Text("inside")
} else if regionState == .outside {
Text("outside")
} else {
Text("unknown")
}
Spacer()
}
}
func removeTask(at offsets: IndexSet) {
for index in offsets {
let task = tasks[index]
managedObjectContext.delete(task)
do {
try managedObjectContext.save()
} catch {
// handle the Core Data error
}
}
}
func showTask(at offsets: IndexSet) {
for index in offsets {
let task = tasks[index]
selectedTask = task.name ?? "No task..."
}
}
}
#if DEBUG
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
#endif
实施Fabian所做的更改后，以下是控制台日志的内容：
After implementing the changes made by Fabian, here is the content of the console log:
已授予：true
2019-08-22 14 ：30：07.051062-0600 AppName [4452：2089841] locationManager（_管理器：CLLocationManager，didChangeAuthorization状态：CLAuthorizationStatus）
2019-08-22 14：30：07.052803-0600 New1Thing [4452：2089841] startScanning
2019-08-22 14：30：07.054319-0600 New1Thing [4452：2089841]当前位置：< + .49945068，-* .87504490> +/- 65.00m（速度-1.00 mps / course -1.00）@ 18/22/19，2:30:07 PM ****白天时间
Granted: true 2019-08-22 14:30:07.051062-0600 AppName[4452:2089841] locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) 2019-08-22 14:30:07.052803-0600 New1Thing[4452:2089841] startScanning 2019-08-22 14:30:07.054319-0600 New1Thing[4452:2089841] Current location: <+.49945068,-*.87504490> +/- 65.00m (speed -1.00 mps / course -1.00) @ 8/22/19, 2:30:07 PM **** Daylight Time
推荐答案
第一关闭，我要感谢Fabian和graycampbell的帮助。
First off I want to thank Fabian and graycampbell for their help.
其次，据我所知，@ ObservableObject仍然有效在使用XCode 11 beta 6的iOS 13 beta 8中无法正常工作。
Secondly, as for as I can tell @ObservableObject still does not work in iOS 13 beta 8 using XCode 11 beta 6.
这对我有用：
1.我更改了
Here is what worked for me: 1. I changed
@ObservedObject var location: MYLocationManager = MYLocationManager()
至：
@EnvironmentObject var location: MYLocationManager
2。在SceneDelegate中，我添加了：
2. In the SceneDelegate I added:
let myLocationManager = MYLocationManager()
and：
window.rootViewController = UIHostingController(rootView: CoreLocationView_NeedsEnv()
.environmentObject(myLocationManager)
不再崩溃！
PS我正在使用Fabian的更新代码。再次感谢！
P.S. I am using Fabian's updated code. Thanks again!
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