ios - iOS 应用程序在后台进行网络请求

Question

我正在创建一个临时应用程序，该应用程序将在我的工作场所分发，以便密切关注我们测试设备的设备充电水平。我让应用程序在后台保持唤醒状态，以使用网络上记录的流行技术检查级别:使用 AVAudioPlayer 播放空白音频文件:see article .

这工作正常，一切都很好，但是应用程序的一个重要部分是它应该使用他们的 web hook API 发布到我们的 slack 帐户，当我这样做时，应用程序似乎被看门狗杀死了:

Incident Identifier: 1CC4B288-4A42-4E4D-9430-58F0FBFF112A
CrashReporter Key:   df80e009afab39b6c94933dd8d9206d4d293f81e
Hardware Model:      iPhone8,2
Process:             Battery [19555]
Path:                /private/var/containers/Bundle/Application/07816F5B-6850-481F-9FA7-6C717BF3946B/Battery.app/Battery
Identifier:          com.yellowbrickbear.Battery
Version:             1 (1.0)
Code Type:           ARM-64 (Native)
Role:                Foreground
Parent Process:      launchd [1]
Coalition:           com.yellowbrickbear.Battery [6957]


Date/Time:           2017-06-22 16:46:41.1031 +0100
Launch Time:         2017-06-22 16:43:36.2253 +0100
OS Version:          iPhone OS 10.3.2 (14F89)
Report Version:      104

Exception Type:  EXC_CRASH (SIGKILL)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note:  EXC_CORPSE_NOTIFY
Termination Reason: Namespace <0xF>, Code 0x8badf00d
Triggered by Thread:  0

Filtered syslog:
None found

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   libsystem_kernel.dylib          0x0000000180623224 mach_msg_trap + 8
1   libsystem_kernel.dylib          0x000000018062309c mach_msg + 72
2   CoreFoundation                  0x00000001815f4e90 __CFRunLoopServiceMachPort + 192
3   CoreFoundation                  0x00000001815f2ae4 __CFRunLoopRun + 1060
4   CoreFoundation                  0x0000000181522da4 CFRunLoopRunSpecific + 424
5   GraphicsServices                0x0000000182f8c074 GSEventRunModal + 100
6   UIKit                           0x00000001877dd058 UIApplicationMain + 208
7   Battery                         0x000000010002e2d4 0x100020000 + 58068
8   libdyld.dylib                   0x000000018053159c start + 4

Thread 1 name:  com.apple.uikit.eventfetch-thread
Thread 1:
0   libsystem_kernel.dylib          0x0000000180623224 mach_msg_trap + 8
1   libsystem_kernel.dylib          0x000000018062309c mach_msg + 72
2   CoreFoundation                  0x00000001815f4e90 __CFRunLoopServiceMachPort + 192
3   CoreFoundation                  0x00000001815f2ae4 __CFRunLoopRun + 1060
4   CoreFoundation                  0x0000000181522da4 CFRunLoopRunSpecific + 424
5   Foundation                      0x000000018203cd74 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 304
6   Foundation                      0x000000018205db44 -[NSRunLoop(NSRunLoop) runUntilDate:] + 96
7   UIKit                           0x00000001881676a8 -[UIEventFetcher threadMain] + 136
8   Foundation                      0x000000018213a2d8 __NSThread__start__ + 996
9   libsystem_pthread.dylib         0x000000018070968c _pthread_body + 240
10  libsystem_pthread.dylib         0x000000018070959c _pthread_body + 0
11  libsystem_pthread.dylib         0x0000000180706cb4 thread_start + 4

Thread 2 name:  AVAudioSession Notify Thread
Thread 2:
0   libsystem_kernel.dylib          0x0000000180623224 mach_msg_trap + 8
1   libsystem_kernel.dylib          0x000000018062309c mach_msg + 72
2   CoreFoundation                  0x00000001815f4e90 __CFRunLoopServiceMachPort + 192
3   CoreFoundation                  0x00000001815f2ae4 __CFRunLoopRun + 1060
4   CoreFoundation                  0x0000000181522da4 CFRunLoopRunSpecific + 424
5   AVFAudio                        0x000000019b866540 GenericRunLoopThread::Entry(void*) + 164
6   AVFAudio                        0x000000019b88c814 CAPThread::Entry(CAPThread*) + 84
7   libsystem_pthread.dylib         0x000000018070968c _pthread_body + 240
8   libsystem_pthread.dylib         0x000000018070959c _pthread_body + 0
9   libsystem_pthread.dylib         0x0000000180706cb4 thread_start + 4

Thread 3 name:  com.apple.coreaudio.AQClient
Thread 3:
0   libsystem_kernel.dylib          0x0000000180623224 mach_msg_trap + 8
1   libsystem_kernel.dylib          0x000000018062309c mach_msg + 72
2   CoreFoundation                  0x00000001815f4e90 __CFRunLoopServiceMachPort + 192
3   CoreFoundation                  0x00000001815f2ae4 __CFRunLoopRun + 1060
4   CoreFoundation                  0x0000000181522da4 CFRunLoopRunSpecific + 424
5   AudioToolbox                    0x00000001845ad9fc GenericRunLoopThread::Entry(void*) + 164
6   AudioToolbox                    0x00000001847814bc CAPThread::Entry(CAPThread*) + 84
7   libsystem_pthread.dylib         0x000000018070968c _pthread_body + 240
8   libsystem_pthread.dylib         0x000000018070959c _pthread_body + 0
9   libsystem_pthread.dylib         0x0000000180706cb4 thread_start + 4

Thread 4:
0   libsystem_pthread.dylib         0x0000000180706ca8 start_wqthread + 0

Thread 5:
0   libsystem_pthread.dylib         0x0000000180706ca8 start_wqthread + 0

我用来发布到 Slack 的代码如下:

DispatchQueue.global(qos: .default).async { [weak self] in
        
    guard let urlComponents = URLComponents(string: "https://hooks.slack.com/services/"), let url = urlComponents.url else { return } // URL shortened so you can't spam us via this S.O!
        
    let urlRequest = NSMutableURLRequest(url: url)
        
    let data = [
        "text": text,
        "channel": /*channel != nil ? channel! :*/ "@simon",
        "icon_emoji": ":passport_control:",
        "username": "Battery Police"
    ]
        
    guard let jsonData = try? JSONSerialization.data(withJSONObject: data, options: []) else {
            return
        }
        
    urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
    urlRequest.httpBody = jsonData
    urlRequest.httpMethod = "POST"
        
    let dataTask = self?.defaultSession?.dataTask(with: urlRequest as URLRequest)
    dataTask?.resume()
}

其中defaultSession是使用后台 session 配置设置的。我正在尝试解决的是为什么这会导致应用程序崩溃，以及我是否可以采取任何措施来阻止看门狗杀死它!

Answer 1

看来这个问题要么是通过@CharlyPico建议使用.background qos创建我的队列来解决的，要么是通过事实上以某种方式调用.play()来解决的我的 AVAudioPlayer 已在提交中删除。我相当确定是前者，因为在某一时刻禁用 API 请求会使应用程序永远运行，因此这很可能是在 .play() 调用被意外删除之前!