【发布时间】：2019-08-22 13:13:55
【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 并在我的设备上安装了 iOS 13 beta 7。
我可以看到两个问题：
-
应用程序崩溃，错误
Thread 1: EXC_BAD_ACCESS出现在147行（...ScrollView {... ） -
CLRegionState 永远不会被调用或不会更新。
我基于 Paul Hudson 的关于 SwiftUI Beacon Detector 的教程（我也无法进行工作），并将其修改为使用 CLRegionState 而不是信标邻近度。
代码如下：
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
实现Fabian所做的更改后，控制台日志的内容如下：
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
【问题讨论】：
标签： ios swift xcode swiftui core-location