我正在构建一个watchOS应用程序，该应用程序需要定期从配套的iPhone应用程序请求信息以刷新复杂功能。
为了实现这一点，我有一个定期运行的WKApplicationRefreshBackgroundTask。它使用来自WatchConnectivitysendMessage(_:replyHandler:errorHandler:)从 iPhone 应用程序请求信息、处理回复并更新复杂功能。
在大多数情况下，这对许多用户来说都是可靠的，但是，我看到与sendMessage(_:replyHandler:errorHandler:)相关的 Xcode 中的 Apple Watch 崩溃，我担心这会导致用户错过复杂的更新。一些用户一直在抱怨并发症没有更新，所以我试图确定是否存在超出 watchOS 中复杂功能刷新频率的常规限制的问题。
有人对如何解决此问题有任何建议吗？或者，您对我如何更好地解决导致崩溃的问题并找出如何防止崩溃有什么建议吗？
我在底部包含了其中一个崩溃的完整示例，以及处理后台任务的代码和处理从配对的iPhone发送和接收值的代码。
我永远不会在没有 replyHandler 的情况下发送消息，所以虽然其他人看到了问题，因为没有处理程序的消息的委托方法没有在 iPhone 上实现，但我认为这不是这里的问题。为了安全起见，我在iPhone上将委托方法实现为一个不执行任何操作的空方法。
2020 年 1 月 30 日更新：一位朋友建议，也许问题在于任务在进行中时被 10 秒计时器标记为完成，导致待处理的内容完成时出现内存问题，但不确定可以做些什么。也许这就是问题的核心？
这是我ExtensionDelegate的后台刷新代码：
func handle(_ backgroundTasks: Set<WKRefreshBackgroundTask>) {
for task in backgroundTasks {
switch task {
case let backgroundTask as WKApplicationRefreshBackgroundTask:
// set a timer in case it doesn't complete
// the maximum allowed is 15 seconds, and then it crashes, so schedule the new task and mark complete after 10
var timeoutTimer: Timer? = Timer.scheduledTimer(withTimeInterval: 10, repeats: false) { (timer) in
self.scheduleBackgroundRefresh()
backgroundTask.setTaskCompletedWithSnapshot(false)
}
// schedule the next refresh now in case the request crashes
scheduleBackgroundRefresh()
WatchConnectivityManager.shared.requestDataFromPhone()
ComplicationManager.shared.reloadComplication()
// as long as the expiration timer is valid, cancel the timer and set the task complete
// otherwise, we'll assume the timer has fired and the task has been marked complete already
// if it's marked complete again, that's a crash
if let timerValid = timeoutTimer?.isValid, timerValid == true {
timeoutTimer?.invalidate()
timeoutTimer = nil
backgroundTask.setTaskCompletedWithSnapshot(true)
}
default:
// make sure to complete unhandled task types
task.setTaskCompletedWithSnapshot(false)
}
}
}
private func scheduleBackgroundRefresh() {
let fiveMinutesFromNow: Date = Date(timeIntervalSinceNow: 5 * 60)
WKExtension.shared().scheduleBackgroundRefresh(withPreferredDate: fiveMinutesFromNow,
userInfo: nil) { (error) in
if let error = error {
fatalError("(error)")
}
}
}
这是WatchConnectivityManager：
import Foundation
import WatchKit
import WatchConnectivity
class WatchConnectivityManager: NSObject {
static let shared = WatchConnectivityManager()
let session = WCSession.default
private let receivedMessageQueue: OperationQueue = {
let queue = OperationQueue()
queue.maxConcurrentOperationCount = 1
return queue
}()
private func process(messageOrUserInfo: [String : Any]) {
receivedMessageQueue.addOperation {
if let recievedValue = messageOrUserInfo["ValueFromPhone"] as? Int {
DispatchQueue.main.async {
ViewModel.shared.valueFromPhone = recievedValue
}
}
}
}
func requestDataFromPhone() {
if session.activationState == .activated {
let message: [String : Any] = ["Request" : true]
let replyHandler: (([String : Any]) -> Void) = { reply in
self.process(messageOrUserInfo: reply)
}
let errorHandler: ((Error) -> Void) = { error in
}
if session.isReachable {
session.sendMessage(message,
replyHandler: replyHandler,
errorHandler: errorHandler)
}
// send a request to the iPhone as a UserInfo in case the message fails
session.transferUserInfo(message)
}
}
}
extension WatchConnectivityManager: WCSessionDelegate {
func session(_ session: WCSession,
activationDidCompleteWith activationState: WCSessionActivationState,
error: Error?) {
if activationState == .activated {
requestDataFromPhone()
}
}
func session(_ session: WCSession,
didReceiveUserInfo userInfo: [String : Any])
{
process(messageOrUserInfo: userInfo)
}
}
崩溃示例：
Hardware Model: Watch3,4
AppVariant: 1:Watch3,4:6
Code Type: ARM (Native)
Role: Non UI
Parent Process: launchd [1]
OS Version: Watch OS 6.1.1 (17S449)
Release Type: User
Baseband Version: n/a
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Subtype: KERN_INVALID_ADDRESS at 0x00000004
VM Region Info: 0x4 is not in any region. Bytes before following region: 638972
REGION TYPE START - END [ VSIZE] PRT/MAX SHRMOD REGION DETAIL
UNUSED SPACE AT START
--->
__TEXT 0009c000-000ac000 [ 64K] r-x/r-x SM=COW ...x/App Name
Termination Signal: Segmentation fault: 11
Termination Reason: Namespace SIGNAL, Code 0xb
Terminating Process: exc handler [377]
Triggered by Thread: 9
Thread 0 name:
Thread 0:
0 libsystem_kernel.dylib 0x4381f864 semaphore_wait_trap + 8
1 libdispatch.dylib 0x436dac26 _dispatch_sema4_wait + 12 (lock.c:139)
2 libdispatch.dylib 0x436db09a _dispatch_semaphore_wait_slow + 104 (semaphore.c:132)
3 FrontBoardServices 0x46de503e -[FBSSceneSnapshotRequestHandle performRequestForScene:] + 408 (FBSSceneSnapshotRequestHandle.m:67)
4 FrontBoardServices 0x46de96ac -[FBSSceneSnapshotAction snapshotRequest:performWithContext:] + 218 (FBSSceneSnapshotAction.m:168)
5 FrontBoardServices 0x46da4320 -[FBSSceneSnapshotRequest performSnapshotWithContext:] + 292 (FBSSceneSnapshotRequest.m:65)
6 UIKitCore 0x5ba6a000 __65-[UIApplication _performSnapshotsWithAction:forScene:completion:]_block_invoke_3 + 168 (UIApplication.m:7655)
7 FrontBoardServices 0x46de9568 -[FBSSceneSnapshotAction _executeNextRequest] + 244 (FBSSceneSnapshotAction.m:135)
8 FrontBoardServices 0x46de91e0 -[FBSSceneSnapshotAction executeRequestsWithHandler:completionHandler:expirationHandler:] + 244 (FBSSceneSnapshotAction.m:87)
9 UIKitCore 0x5ba69f20 __65-[UIApplication _performSnapshotsWithAction:forScene:completion:]_block_invoke_2 + 238 (UIApplication.m:7650)
10 UIKitCore 0x5ba69696 -[UIApplication _beginSnapshotSessionForScene:withSnapshotBlock:] + 772 (UIApplication.m:7582)
11 UIKitCore 0x5ba69e16 __65-[UIApplication _performSnapshotsWithAction:forScene:completion:]_block_invoke + 112 (UIApplication.m:7648)
12 UIKitCore 0x5b2c1110 -[UIScene _enableOverrideSettingsForActions:] + 40 (UIScene.m:1206)
13 UIKitCore 0x5b2c1330 -[UIScene _performSystemSnapshotWithActions:] + 112 (UIScene.m:1230)
14 UIKitCore 0x5ba69b90 -[UIApplication _performSnapshotsWithAction:forScene:completion:] + 382 (UIApplication.m:7647)
15 UIKitCore 0x5be89586 __98-[_UISceneSnapshotBSActionsHandler _respondToActions:forFBSScene:inUIScene:fromTransitionCont... + 146 (_UISceneSnapshotBSActionsHandler.m:54)
16 UIKitCore 0x5ba68fd4 _runAfterCACommitDeferredBlocks + 274 (UIApplication.m:3038)
17 UIKitCore 0x5ba5b3da _cleanUpAfterCAFlushAndRunDeferredBlocks + 198 (UIApplication.m:3016)
18 UIKitCore 0x5ba82702 _afterCACommitHandler + 56 (UIApplication.m:3068)
19 CoreFoundation 0x43b63644 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 18 (CFRunLoop.c:1758)
20 CoreFoundation 0x43b5f43c __CFRunLoopDoObservers + 350 (CFRunLoop.c:1868)
21 CoreFoundation 0x43b5f956 __CFRunLoopRun + 1150 (CFRunLoop.c:2910)
22 CoreFoundation 0x43b5f23a CFRunLoopRunSpecific + 370 (CFRunLoop.c:3192)
23 GraphicsServices 0x46973cd0 GSEventRunModal + 96 (GSEvent.c:2246)
24 UIKitCore 0x5ba61580 UIApplicationMain + 1730 (UIApplication.m:4773)
25 libxpc.dylib 0x438fbcf0 _xpc_objc_main.cold.3 + 152
26 libxpc.dylib 0x438eca34 _xpc_objc_main + 184 (main.m:126)
27 libxpc.dylib 0x438ee934 xpc_main + 110 (init.c:1568)
28 Foundation 0x443f3156 -[NSXPCListener resume] + 172 (NSXPCListener.m:276)
29 PlugInKit 0x4b58b26c -[PKService run] + 384 (PKService.m:165)
30 WatchKit 0x52e9dafe WKExtensionMain + 62 (main.m:19)
31 libdyld.dylib 0x43715e82 start + 2
Thread 1 name:
Thread 1:
0 libsystem_kernel.dylib 0x4381f814 mach_msg_trap + 20
1 libsystem_kernel.dylib 0x4381eece mach_msg + 42 (mach_msg.c:103)
2 CoreFoundation 0x43b63946 __CFRunLoopServiceMachPort + 152 (CFRunLoop.c:2575)
3 CoreFoundation 0x43b5f9de __CFRunLoopRun + 1286 (CFRunLoop.c:2931)
4 CoreFoundation 0x43b5f23a CFRunLoopRunSpecific + 370 (CFRunLoop.c:3192)
5 Foundation 0x443bf398 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 180 (NSRunLoop.m:374)
6 Foundation 0x443bf2b4 -[NSRunLoop(NSRunLoop) runUntilDate:] + 76 (NSRunLoop.m:421)
7 UIKitCore 0x5badf012 -[UIEventFetcher threadMain] + 140 (UIEventFetcher.m:637)
8 Foundation 0x444c1b60 __NSThread__start__ + 708 (NSThread.m:724)
9 libsystem_pthread.dylib 0x438ad1ac _pthread_start + 130 (pthread.c:896)
10 libsystem_pthread.dylib 0x438b3f28 thread_start + 20
Thread 2 name:
Thread 2:
0 libsystem_kernel.dylib 0x43836d04 __psynch_cvwait + 24
1 libsystem_pthread.dylib 0x438b02c2 _pthread_cond_wait + 496 (pthread_cond.c:591)
2 libsystem_pthread.dylib 0x438aca4a pthread_cond_wait + 38 (pthread_cancelable.c:558)
3 Foundation 0x444381f0 -[NSOperation waitUntilFinished] + 446 (NSOperation.m:737)
4 Foundation 0x444a5302 __NSOPERATIONQUEUE_IS_WAITING_ON_AN_OPERATION__ + 22 (NSOperation.m:2610)
5 Foundation 0x444222ee -[NSOperationQueue addOperations:waitUntilFinished:] + 128 (NSOperation.m:2618)
6 WatchConnectivity 0x53f9871e __47-[WCSession handleUserInfoResultWithPairingID:]_block_invoke.491 + 540 (WCSession.m:1440)
7 WatchConnectivity 0x53fa5608 -[WCFileStorage enumerateUserInfoResultsWithBlock:] + 1564 (WCFileStorage.m:505)
8 WatchConnectivity 0x53f984ca __47-[WCSession handleUserInfoResultWithPairingID:]_block_invoke_2 + 284 (WCSession.m:1430)
9 Foundation 0x444a4794 __NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 10 (NSOperation.m:1541)
10 Foundation 0x443d2f7a -[NSBlockOperation main] + 74 (NSOperation.m:1560)
11 Foundation 0x444a63e2 __NSOPERATION_IS_INVOKING_MAIN__ + 22 (NSOperation.m:2184)
12 Foundation 0x443d2b96 -[NSOperation start] + 578 (NSOperation.m:2201)
13 Foundation 0x444a6b7c __NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 22 (NSOperation.m:2215)
14 Foundation 0x444a6798 __NSOQSchedule_f + 134 (NSOperation.m:2226)
15 libdispatch.dylib 0x436d9846 _dispatch_call_block_and_release + 10 (init.c:1408)
16 libdispatch.dylib 0x436da8b8 _dispatch_client_callout + 6 (object.m:495)
17 libdispatch.dylib 0x436dc6f8 _dispatch_continuation_pop + 330 (inline_internal.h:2484)
18 libdispatch.dylib 0x436dc08c _dispatch_async_redirect_invoke + 520 (queue.c:803)
19 libdispatch.dylib 0x436e6eac _dispatch_root_queue_drain + 540 (inline_internal.h:2525)
20 libdispatch.dylib 0x436e73e0 _dispatch_worker_thread2 + 98 (queue.c:6628)
21 libsystem_pthread.dylib 0x438aecd2 _pthread_wqthread + 158 (pthread.c:2364)
22 libsystem_pthread.dylib 0x438b3f10 start_wqthread + 20
Thread 3:
0 libsystem_pthread.dylib 0x438b3efc start_wqthread + 0
Thread 4:
0 libsystem_pthread.dylib 0x438b3efc start_wqthread + 0
Thread 5:
0 libsystem_pthread.dylib 0x438b3efc start_wqthread + 0
Thread 6 name:
Thread 6:
0 libsystem_kernel.dylib 0x43838c6c kevent_qos + 24
1 libdispatch.dylib 0x436f2b74 _dispatch_kq_poll + 204 (event_kevent.c:736)
2 libdispatch.dylib 0x436f280a _dispatch_kq_drain + 96 (event_kevent.c:809)
3 libdispatch.dylib 0x436f2196 _dispatch_event_loop_poke + 162 (event_kevent.c:1918)
4 libdispatch.dylib 0x436e32b8 _dispatch_mgr_queue_push + 110 (queue.c:5857)
5 WatchConnectivity 0x53f9aa26 -[WCSession createAndStartTimerOnWorkQueueWithHandler:] + 150 (WCSession.m:1803)
6 WatchConnectivity 0x53f90790 -[WCSession onqueue_sendMessageData:replyHandler:errorHandler:dictionaryMessage:] + 382 (WCSession.m:674)
7 WatchConnectivity 0x53f901da __51-[WCSession sendMessage:replyHandler:errorHandler:]_block_invoke.256 + 190 (WCSession.m:630)
8 Foundation 0x444a4794 __NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 10 (NSOperation.m:1541)
9 Foundation 0x443d2f7a -[NSBlockOperation main] + 74 (NSOperation.m:1560)
10 Foundation 0x444a63e2 __NSOPERATION_IS_INVOKING_MAIN__ + 22 (NSOperation.m:2184)
11 Foundation 0x443d2b96 -[NSOperation start] + 578 (NSOperation.m:2201)
12 Foundation 0x444a6b7c __NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 22 (NSOperation.m:2215)
13 Foundation 0x444a6798 __NSOQSchedule_f + 134 (NSOperation.m:2226)
14 libdispatch.dylib 0x436e4c02 _dispatch_block_async_invoke2 + 80 (queue.c:525)
15 libdispatch.dylib 0x436da8b8 _dispatch_client_callout + 6 (object.m:495)
16 libdispatch.dylib 0x436dc6f8 _dispatch_continuation_pop + 330 (inline_internal.h:2484)
17 libdispatch.dylib 0x436dc08c _dispatch_async_redirect_invoke + 520 (queue.c:803)
18 libdispatch.dylib 0x436e6eac _dispatch_root_queue_drain + 540 (inline_internal.h:2525)
19 libdispatch.dylib 0x436e73e0 _dispatch_worker_thread2 + 98 (queue.c:6628)
20 libsystem_pthread.dylib 0x438aecd2 _pthread_wqthread + 158 (pthread.c:2364)
21 libsystem_pthread.dylib 0x438b3f10 start_wqthread + 20
Thread 7:
0 libsystem_pthread.dylib 0x438b3efc start_wqthread + 0
Thread 8:
0 libsystem_pthread.dylib 0x438b3efc start_wqthread + 0
Thread 9 name:
Thread 9 Crashed:
0 libdispatch.dylib 0x436eacec dispatch_channel_cancel + 6 (source.c:1020)
1 WatchConnectivity 0x53f909c6 __81-[WCSession onqueue_sendMessageData:replyHandler:errorHandler:dictionaryMessage:]_block_invoke + 42 (WCSession.m:675)
2 libdispatch.dylib 0x436da8b8 _dispatch_client_callout + 6 (object.m:495)
3 libdispatch.dylib 0x436dc6f8 _dispatch_continuation_pop + 330 (inline_internal.h:2484)
4 libdispatch.dylib 0x436ea81e _dispatch_source_invoke + 1758 (source.c:568)
5 libdispatch.dylib 0x436e6eac _dispatch_root_queue_drain + 540 (inline_internal.h:2525)
6 libdispatch.dylib 0x436e73e0 _dispatch_worker_thread2 + 98 (queue.c:6628)
7 libsystem_pthread.dylib 0x438aecd2 _pthread_wqthread + 158 (pthread.c:2364)
8 libsystem_pthread.dylib 0x438b3f10 start_wqthread + 20
Thread 10:
0 libsystem_pthread.dylib 0x438b3efc start_wqthread + 0
Thread 11:
0 libsystem_pthread.dylib 0x438b3efc start_wqthread + 0
Thread 9 crashed with ARM Thread State (32-bit):
r0: 0x00000000 r1: 0x80000000 r2: 0x00000001 r3: 0x7fffffff
r4: 0x16548f40 r5: 0x00000000 r6: 0x00000110 r7: 0x3f057e58
r8: 0x00000000 r9: 0x00000000 r10: 0x00000000 r11: 0x00401600
ip: 0x66e39628 sp: 0x3f057e30 lr: 0x53f909c7 pc: 0x436eacec
cpsr: 0x80000030
我假设你的朋友是对的：
当你将后台任务设置为完成时，系统将暂停你的应用程序，见这里。
系统可以在没有警告的情况下清除暂停的应用程序，请参阅此处。
因此，如果发生这种情况，则无法调用replyHandler或errorHandler，并且应用程序崩溃。
因此，您不能依靠sendMessage来唤醒iOS应用程序并及时呼叫replyHandler。
我建议您在iOS上初始化复杂数据的传输。要定期执行此操作，您可以使用静默推送通知来唤醒您的 iOS 应用程序，并使用此处transferCurrentComplicationUserInfo(_:)发送新的并发症数据。即使您的手表应用程序未运行，也会收到此userInfo，并且可以根据需要更新复杂功能数据。
编辑：
虽然我上面的解决方案可能有效，但可能有一个更简单的解决方案：
也许不需要更新您的ViewModel以响应sendMessage，只需要并发症。如果是这样，您可以简单地使用sendMessage，replyHandler和errorHandler设置为nil.sendMessage保证将来唤醒 iOS 应用程序，即使 watchOS 应用程序已经处于非活动状态也是如此。然后，iOS应用程序可以发送并发症数据，这些数据将立即显示。
此外，iOS 应用可以将更新ViewModel的userInfo作为应用程序上下文发送。然后，当watchOS应用程序再次处于活动状态时，它将可用，您可以 更新ViewModel。
如果这适合您的用例，您只需删除计时器并在sendMessage后立即完成后台任务。