OSLog is a unified logging system for the reading of historical data.

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Your Friend the System Log
The unified system log on Apple platforms gets a lot of stick for being ‘too verbose’. I understand that perspective: If you’re used to a traditional Unix-y system log, you might expect to learn something about an issue by manually looking through the log, and the unified system log is way too chatty for that. However, that’s a small price to pay for all its other benefits. This post is my attempt to explain those benefits, broken up into a series of short bullets. Hopefully, by the end, you’ll understand why I’m best friends with the system log, and why you should be too! If you have questions or comments about this, start a new thread and tag it with OSLog so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Your Friend the System Log Apple’s unified system log is very powerful. If you’re writing code for any Apple platform, and especially if you’re working on low-level code, it pays to become friends with the system log! The Benefits of Having a Such Good Friend The public API for logging is fast and full-featured. And it’s particularly nice in Swift. Logging is fast enough to leave log points [1] enabled in your release build, which makes it easier to debug issues that only show up in the field. The system log is used extensively by the OS itself, allowing you to correlate your log entries with the internal state of the system. Log entries persist for a long time, allowing you to investigate an issue that originated well before you noticed it. Log entries are classified by subsystem, category, and type. Each type has a default disposition, which determines whether that log entry is enable and, if it is, whether it persists in the log store. You can customise this, based on the subsystem, category, and type, in four different ways: Install a configuration profile created by Apple (all platforms). Add an OSLogPreferences property to your app’s Info.plist (all platforms). Run the log tool with the config command (macOS only) Create and install a custom configuration profile with the com.apple.system.logging payload (macOS only). When you log a value, you may tag it as private. These values are omitted from the log by default but you can configure the system to include them. For information on how to do that, see Recording Private Data in the System Log. The Console app displays the system log. On the left, select either your local Mac or an attached iOS device. Console can open and work with log snapshots (.logarchive). It also supports surprisingly sophisticated searching. For instructions on how to set up your search, choose Help > Console Help. Console’s search field supports copy and paste. For example, to set up a search for the subsystem com.foo.bar, paste subsystem:com.foo.bar into the field. Console supports saved searches. Again, Console Help has the details. Console supports viewing log entries in a specific timeframe. By default it shows the last 5 minutes. To change this, select an item in the Showing popup menu in the pane divider. If you have a specific time range of interest, select Custom, enter that range, and click Apply. Instruments has os_log and os_signpost instruments that record log entries in your trace. Use this to correlate the output of other instruments with log points in your code. Instruments can also import a log snapshot. Drop a .logarchive file on to Instruments and it’ll import the log into a trace document, then analyse the log with Instruments’ many cool features. The log command-line tool lets you do all of this and more from Terminal. There’s a public API to read back existing log entries, albeit one with significant limitations on iOS (more on that below). Every sysdiagnose log includes a snapshot of the system log, which is ideal for debugging hard-to-reproduce problems. For more details on that, see Using a Sysdiagnose Log to Debug a Hard-to-Reproduce Problem. For general information about sysdiagnose logs, see Bug Reporting > Profiles and Logs. But you don’t have to use sysdiagnose logs. To create a quick snapshot of the system log, run the log tool with the collect subcommand. If you’re investigating recent events, use the --last argument to limit its scope. For example, the following creates a snapshot of log entries from the last 5 minutes: % sudo log collect --last 5m For more information, see: os > Logging OSLog log man page os_log man page (in section 3) os_log man page (in section 5) WWDC 2016 Session 721 Unified Logging and Activity Tracing [1] Well, most log points. If you’re logging thousands of entries per second, the very small overhead for these disabled log points add up. Foster Your Friendship Good friendships take some work on your part, and your friendship with the system log is no exception. Follow these suggestions for getting the most out of the system log. The system log has many friends, and it tries to love them the all equally. Don’t abuse that by logging too much. One key benefit of the system log is that log entries persist for a long time, allowing you to debug issues with their roots in the distant past. But there’s a trade off here: The more you log, the shorter the log window, and the harder it is to debug such problems. Put some thought into your subsystem and category choices. One trick here is to use the same category across multiple subsystems, allowing you to track issues as they cross between subsystems in your product. Or use one subsystem with multiple categories, so you can search on the subsystem to see all your logging and then focus on specific categories when you need to. Don’t use too many unique subsystem and context pairs. As a rough guide: One is fine, ten is OK, 100 is too much. Choose your log types wisely. The documentation for each OSLogType value describes the default behaviour of that value; use that information to guide your choices. Remember that disabled log points have a very low cost. It’s fine to leave chatty logging in your product if it’s disabled by default. No Friend Is Perfect The system log API is hard to wrap. The system log is so efficient because it’s deeply integrated with the compiler. If you wrap the system log API, you undermine that efficiency. For example, a wrapper like this is very inefficient: -*-*-*-*-*- DO NOT DO THIS -*-*-*-*-*- void myLog(const char * format, ...) { va_list ap; va_start(ap, format); char * str = NULL; vasprintf(&str, format, ap); os_log_debug(sLog, "%s", str); free(str); va_end(ap); } -*-*-*-*-*- DO NOT DO THIS -*-*-*-*-*- This is mostly an issue with the C API, because the modern Swift API is nice enough that you rarely need to wrap it. If you do wrap the C API, use a macro and have that pass the arguments through to the underlying os_log_xyz macro. iOS has very limited facilities for reading the system log. Currently, an iOS app can only read entries created by that specific process, using .currentProcessIdentifier scope. This is annoying if, say, the app crashed and you want to know what it was doing before the crash. What you need is a way to get all log entries written by your app (r. 57880434). There are two known bugs with the .currentProcessIdentifier scope. The first is that the .reverse option doesn’t work (r. 87622922). You always get log entries in forward order. The second is that the getEntries(with:at:matching:) method doesn’t honour its position argument (r. 87416514). You always get all available log entries. Xcode 15 beta has a shiny new console interface. For the details, watch WWDC 2023 Session 10226 Debug with structured logging. For some other notes about this change, search the Xcode 15 Beta Release Notes for 109380695. In older versions of Xcode the console pane was not a system log client (r. 32863680). Rather, it just collected and displayed stdout and stderr from your process. This approach had a number of consequences: The system log does not, by default, log to stderr. Xcode enabled this by setting an environment variable, OS_ACTIVITY_DT_MODE. The existence and behaviour of this environment variable is an implementation detail and not something that you should rely on. Xcode sets this environment variable when you run your program from Xcode (Product > Run). It can’t set it when you attach to a running process (Debug > Attach to Process). Xcode’s Console pane does not support the sophisticated filtering you’d expect in a system log client. When I can’t use Xcode 15, I work around the last two by ignoring the console pane and instead running Console and viewing my log entries there. If you don’t see the expected log entries in Console, make sure that you have Action > Include Info Messages and Action > Include Debug Messages enabled. The system log interface is available within the kernel but it has some serious limitations. Here’s the ones that I’m aware of: This is no subsystem or category support )-: There is no support for annotations like {public} and {private}. Adding such annotations causes the log entry to be dropped (r. 40636781). Revision History 2023-10-20 Added some Instruments tidbits. 2023-10-13 Described a second known bug with the .currentProcessIdentifier scope. Added a link to Using a Sysdiagnose Log to Debug a Hard-to-Reproduce Problem. 2023-08-28 Described a known bug with the .reverse option in .currentProcessIdentifier scope. 2023-06-12 Added a call-out to the Xcode 15 Beta Release Notes. 2023-06-06 Updated to reference WWDC 2023 Session 10226. Added some notes about the kernel’s system log support. 2023-03-22 Made some minor editorial changes. 2023-03-13 Reworked the Xcode discussion to mention OS_ACTIVITY_DT_MODE. 2022-10-26 Called out the Showing popup in Console and the --last argument to log collect. 2022-10-06 Added a link WWDC 2016 Session 721 Unified Logging and Activity Tracing. 2022-08-19 Add a link to Recording Private Data in the System Log. 2022-08-11 Added a bunch of hints and tips. 2022-06-23 Added the Foster Your Friendship section. Made other editorial changes. 2022-05-12 First posted.
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5.6k
Oct ’23
"Enable-Private-Data" in a command line application ..
I've read the definitive "Recording Private Data in the System Log" by @eskimo and the words at man 5 os_log and written code to, specifically, turn on "Enable-Private-Data" in my app. My application is a command line and I've configured Xcode to insert what I believe to be the appropriate incantations in an Info.plist file into the unstructured executable binary. When I run the app with Terminal, I see <private> output in the Console app where I expect values to be displayed in a public manner. Nothing I've read says that <key>Enable-Private-Data</key><true/> doesn't apply to command line apps, and my own understanding of the value of of the logging mechanism rejects that notion because logging is performed all over macOS, not just in a ***.app environment. A this point, I'm firmly convinced this unexpected behavior is of my own doing, but I have paused the search for my (probably embarrassing) mistake, to write this note because of a 1% doubt I'm wrong. I'd be very happy to receive the, expected, assurance that logging configuration via an embedded Info.plist in a command line app does influence logging behavior. With that assurance, I'll know it's my problem and I'll search/find/fix. On there way there, I'll create the simplest command line app that exhibits this anomaly -- which will likely reveal my error and, if not, it'll be fodder for a bug report. Embedding an Info.plist into a command line app is a tad out of the ordinary but I've done it before (using Xcode or SPM) to carry knowledge into a CLI via a mainBundle.infoDictionary .. and in the particular case described above, I've printed that infoDictionary to show the successful embedding, viz: . . . . "OSLogPreferences": { "com.ramsaycons" = { "DEFAULT-OPTIONS" = { "Enable-Private-Data" = 1; }; }; }, . . . . Sonoma 14.5 / Xcode 15.4 / MBP (Apple M1 Max)
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3w
Timestamped Xcode Log Message How do I parse this to find source of error?
with the latest Xcode that runs with Mac OS 14.5 Developer Beta has messages with a time and date in them There are also some other fields of an indeterminate origin/type. "2024-05-06 15:37:32.383996-0500 RoomPlanExampleApp[24190:1708576] [CAMetalLayerDrawable texture] should not be called after already presenting this drawable. Get a nextDrawable instead." specifically I need to know how the string [24190:1708576] relates to a location in my application so I can act on the message. I certainly can't find the text in the "[CAMetalLayerDrawable texture]". field anywhere in the user documentation OR the Development documentation. In order for a diagnostic message to be Actionable and remedied by a user it must identify the module and source line of the initiating code and there must be accessible documentation for users to access to get an explanation of potential remedies.. This interface fails to supply enough information to diagnose the problem. The label in [CAMetalLayerDrawable texture] cannot even be found in a search of the package information attached to the Xcode Release paired with the IOS and Mac OS system releases.
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243
May ’24
macOS 14.4.1 borked or locked system log --stream
To help with debugging on a customers machine, this terminal command records log entries for my app and writes 'em to disk. log stream --predicate 'process=="Sleep Aid"' --style compact &gt; ~/Desktop/Sleep\ Aid.log In my app I have a function that does something similar to the above with a NSTask, and then I ask the customer to repeat the action that causes the problem. However for one customer, the file is created, but apart from it saying it's being filter by process, nothing else is written. Is there some new security setting that can prevent an app from getting its own logging data, or in this case even prevent the customer from using terminal and the above command to get the log data? This is similar also. https://forums.developer.apple.com/forums/thread/743803 Or should I be filing a radar about a potential bug?
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237
Apr ’24
Strings do not get redacted in OSLogMessages despite OSLogPrivacy options
I have read several times https://developer.apple.com/forums/thread/705868 https://developer.apple.com/forums/thread/705810 https://developer.apple.com/documentation/os/logging/generating_log_messages_from_your_code#3665948 From what I understand code like this: import SwiftUI import OSLog struct ContentView: View { private static let logger = Logger(subsystem: "HCP", category: "ContentView") var myprivateData: Date { Date() } var myprivateData2: String { "bank-account-111-222-333" } let myprivateData3: String = "bank-account-111-222-333" var body: some View { VStack { Image(systemName: "globe") .imageScale(.large) .foregroundStyle(.tint) Text("Hello, world!") } .padding() .onAppear(perform: { Self.logger.info("test info") Self.logger.info("test info \(myprivateData)") Self.logger.info("test info \(myprivateData2)") Self.logger.info("test info \(myprivateData3)") Self.logger.info("test info") Self.logger.info("test info \(myprivateData, privacy: .private)") Self.logger.info("test info \(myprivateData2, privacy: .private)") Self.logger.info("test info \(myprivateData3, privacy: .private)") }) } } Should result in somewhat redacted log messages, so my expectation would be that dynamic strings Self.logger.info("test info1") Self.logger.info("test info2 \(myprivateData)") Self.logger.info("test info3 \(myprivateData2)") Self.logger.info("test info4 \(myprivateData3)") would result in logs like: info 21:29:07.877698+0200 TestOsLogger test info1 info 21:29:07.877757+0200 TestOsLogger test info2 <private> info 21:29:07.877800+0200 TestOsLogger test info3 <private> info 21:29:07.877835+0200 TestOsLogger test info4 <private> instead I get info 21:29:07.874356+0200 TestOsLogger test info1 info 21:29:07.877531+0200 TestOsLogger test info2 <private> info 21:29:07.877615+0200 TestOsLogger test info3 bank-account-111-222-333 info 21:29:07.877656+0200 TestOsLogger test info4 bank-account-111-222-333 where clearly date object got redacted, but string not really. Adding privacy: .private helps here, but it is still a different behavior from what I expected after reading docs. Is that a change or rather my misunderstanding? Eskimo for the rescue?
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285
Apr ’24
OSLog messages not showing in system log
Since MacOS 14.4 I've been having trouble seeing logs emitted from my applications with oslog. For example: #import <Foundation/Foundation.h> #include <os/log.h> int main(int argc, const char * argv[]) { @autoreleasepool { os_log_error(OS_LOG_DEFAULT, "Hello World!"); } return 0; } When I compile and run this in Xcode I do see the log message in Xcode itself. But I'm not able to see anything with log stream --source --predicate "eventMessage contains 'Hello'" or the Console.app if I run the same program in Xcode or outside. I do see logs from other applications on the same machine so it's not completely down. Any suggestions on how to debug this? Perhaps something missing in the project that would "enable" logging?
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333
Apr ’24
Can i do cellular call from my iOS app without user interaction and send message to particular number without user interaction in iOS swift.
My requirement is here- 1- We need to implement functionality in my iOS app to do call (cellular call) without user interaction. 2- We need to implement functionality in my iOS app to send normal message to particular phone number without user interaction. 3- Fetch OS log (NOT MY APPLICATION LOG). we need to fetch OS log when cellular call going on in device this log need to collect in my iOS app for identify the network strength and other things like call is connected and disconnect etc. Thanks
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360
Mar ’24
os_signpost not working on macOS device, works on iOS device
I have an iOS app that uses os_signpost API for instrumentation. When I profile it from Xcode on real iOS device, it works as expected. When I profile its macCatalyst variant (using the identical code) on the same Mac where Xcode is running, the os_signpost Instrument does not show anything, not even the Apple provided signposts that are otherwise visible on the iOS. How do I make it work?
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615
1w
Is OSLog Logger Sendable?
The new Xcode 15.3 Release Candidate produces errors with strict concurrency checking that the usual pattern of using OSLog with a static property like static let logger = Logger(...) is not safe. "Static property 'logger' is not concurrency-safe because it is not either conforming to 'Sendable' or isolated to a global actor; this is an error in Swift 6" Is Logger thread safe and just not marked Sendable? Would it be "safe" to use nonisolated(unsafe) static let logger = Logger(...)?
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1.6k
Mar ’24
Debug level logs not collected by log collect command
I am using sudo log collect --device-udid {device-udid} --last 7m command to collect console.app logs . But it seems only info and error logs are getting collected in logarchive file even though I can se debug level logs getting printed in console.app . How we can change the level to collect debug level logs as well from console app. Options log collect command have -: --device Collect logs from first device found --device-name Collect logs from device with the given name --device-udid Collect logs from device with the given UDID --last [m|h|d] Collect logs starting [m|h|d] ago -output Output log archive to the given path --size [k|m] Limit log collection to the given size --start Collect logs starting at the given time There is no way to provide debug level in command .
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380
Mar ’24
Help Identifying Hidden Bundle ID in Logs for MDM Whitelist Configuration
I've encountered an issue while reviewing logs from my device and hope someone here can shed some light on it. In the process of diagnosing an application behavior, I noticed that some entries in my logs are marked as , specifically next to bundle IDs, which makes it challenging to understand which app or process is involved. Here are the relevant log entries: Feb 21 17:40:53 vCw-2 suggestd(CoreSuggestionsInternals)[30399] &lt;Notice&gt;: SGDSuggestManager: realtimeSuggestionsForMailOrMessageWithHash: com.apple.MobileSMS : &lt;private&gt; Feb 21 17:40:53 vCw-2 suggestd(CoreSuggestionsInternals)[30399] &lt;Notice&gt;: SGDSuggestManager: realtimeSuggestionsForMailOrMessageWithHash: &lt;private&gt;: results: (null) Feb 21 17:40:53 vCw-2 suggestd(CoreSuggestionsInternals)[30399] &lt;Notice&gt;: SGDSuggestManager: realtimeSuggestionsForMailOrMessageWithHash: com.apple.MobileSMS : &lt;private&gt; Feb 21 17:40:53 vCw-2 suggestd(CoreSuggestionsInternals)[30399] &lt;Notice&gt;: SGDSuggestManager: starting dissection. The identification of this hidden bundle ID is essential for allowing the specific iMessage Business Chat feature to function as intended in our MDM-managed devices. Does anyone have insights into why the bundle ID might be hidden or how to uncover it? Are there tools or methods available that could help me identify this bundle ID for MDM whitelist configuration purposes? I appreciate any guidance or recommendations you can provide. Thank you for your time and assistance.
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421
Feb ’24
Xcode 15 console logging of system messages
Background I have a SwiftUI app that uses OSLog and the new Logger framework. In my SwiftUI views, I would like to use something like Self._logChanges() to help debug issues. After some trial and error, I can see the messages appear in the System console log for the app I am debugging using the com.apple.SwiftUI subsystem. Problem I'd like to see those same messages directly in Xcode's console window so I can filter them as needed. How do I do that? Thanks! -Patrick
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921
Feb ’24
Collect logs from OSLog during app background transition cause crash
We use OSLog to log message in our iOS app and retrieve logs to save into local file when app goes to background. This way we will be able to persist logs after app terminated. However, when logs become large, retrieving logs takes more than 5 seconds during background transition that cause our app being killed by the system with below info: Exception Type: EXC_CRASH (SIGKILL) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: FRONTBOARD 2343432205 <RBSTerminateContext| domain:10 code:0x8BADF00D explanation:scene-update watchdog transgression: app<com.cisco.secureclient.zta(B7AB7300-8A17-4C71-88BC-BA3D55AF6666)>:1261 exhausted real (wall clock) time allowance of 10.00 seconds ProcessVisibility: Background ProcessState: Running WatchdogEvent: scene-update WatchdogVisibility: Background WatchdogCPUStatistics: ( "Elapsed total CPU time (seconds): 13.500 (user 10.890, system 2.610), 21% CPU", "Elapsed application CPU time (seconds): 2.119, 3% CPU" ) reportType:CrashLog maxTerminationResistance:Interactive> Triggered by Thread: 0 Thread 0 name: Dispatch queue: com.apple.main-thread Thread 0 Crashed: 0 libsystem_kernel.dylib 0x1ed6e01d8 mach_msg2_trap + 8 1 libsystem_kernel.dylib 0x1ed6dff70 mach_msg2_internal + 80 2 libsystem_kernel.dylib 0x1ed6dfe88 mach_msg_overwrite + 436 3 libsystem_kernel.dylib 0x1ed6dfcc8 mach_msg + 24 4 libdispatch.dylib 0x1aea4df00 _dispatch_mach_send_and_wait_for_reply + 540 5 libdispatch.dylib 0x1aea4e2a0 dispatch_mach_send_with_result_and_wait_for_reply + 60 6 libxpc.dylib 0x20fd406d0 xpc_connection_send_message_with_reply_sync + 264 7 Foundation 0x1a5ad96c0 NSXPCCONNECTION_IS_WAITING_FOR_A_SYNCHRONOUS_REPLY + 16 8 Foundation 0x1a5ac13bc -[NSXPCConnection _sendInvocation:orArguments:count:methodSignature:selector:withProxy:] + 2160 9 Foundation 0x1a5aec6cc -[NSXPCConnection _sendSelector:withProxy:arg1:] + 116 10 Foundation 0x1a5aec604 _NSXPCDistantObjectSimpleMessageSend1 + 60 11 OSLog 0x1f4b98118 -[OSLogCurrentProcessEnumerator nextObject] + 192 12 libswiftOSLog.dylib 0x213983270 OSLogStore.PrivateIterator.next() + 32 13 libswiftOSLog.dylib 0x213983324 protocol witness for IteratorProtocol.next() in conformance OSLogStore.PrivateIterator + 28 14 libswiftCore.dylib 0x1a0050ed0 _IteratorBox.next() + 108 15 MyApp 0x104359e28 static MyLogger.getFormattedLogs() (in MyApp ) (MyLogger.swift:63) + 122408 Here is our code to retrieve logs: struct MyLogger { public var log: Logger init(subsystem: String = getSubsystem(), file: String = #file, function: String = #function, line: Int = #line, context: String = "myapp") { let category = "\(context): \(file): \(line): \(function): " log = Logger(subsystem: subsystem, category: category) } static func getFormattedLogs() -> [String] { do { // Combine log message with timestamp and category with // file/line/function information let df = DateFormatter() df.dateFormat = ZtaConstants.DATE_FORMAT let store = try OSLogStore.init(scope: .currentProcessIdentifier) let logEntries = try store.getEntries() .compactMap{ $0 as? OSLogEntryLog} .filter { $0.subsystem.contains(getSubsystem() } .map{df.string(from: $0.date) + " " + String(format:"0x%02x", $0.threadIdentifier) + " " + String(format:"0x%x", $0.activityIdentifier) + " " + String($0.processIdentifier) + " " + $0.category + " " + $0.composedMessage} return formattedLogs } catch let err { ZtaLogger().log.error("Failed to collect log: \(err)") return [] } } } It looks like getFormattedLogs() takes long time because we use filter to get message that logged by our app and format the log entry. Since compactMap is O(m+n) complexity, filter and map are O(n) that cause performance issue. Is there a better way to get logs from our app via OSLog? Could retrieving logs be called in appDidEnterBackground()? Thanks, Ying
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488
Feb ’24
System logging messages disappear after about 90 seconds
I'm having an issue with logging on my system (Sonoma 14.3.1), in that log messages disappear after 60-90 seconds, despite logging being configured to persist. This seems to happen across all subsystems. The symptoms are: • Watching the log stream in Console.app, messages older than 60-90 seconds disappear, even if no new messages are coming in. • log show --last 2d only returns messages from the last couple of minutes. I've filed FB13616761, but wondered if anyone had any other insights or suggestions. TIA
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380
Feb ’24
iOS: Can OSLogPreferences applied to Xcode console?
I'm trying to figure out how to maximize the value of structured logging in my project. The log filtering improvements in Xcode 15 are great but limited to being able to control the logging at a fine-grained level. For example, if I want to always disable some chatty debug logs for a specific category. Setting OSLogPreference solves this problem once you've installed it onto a device, but when running in debug mode on Xcode, it seems to ignore this and print everything. Is there a way to apply OSLogPreference while running Xcode, or another way to selectively disable categories?
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621
Jan ’24
Can I access system logs from Swift (I want logs for previous runs of my application)
Hi folks, For accessing the logs, I’m using OSLogStore object. I want to be able to read logs from any previous run of my application. I can of course do this: // Open the log store. var logStore = try OSLogStore(scope: .currentProcessIdentifier) But this only allows me to retrieve logs from my current running process. I can also do this: // Open the log store. var logStore = try OSLogStore(scope: .system) But this only works if my App Sandbox entitlement is false. I tried disabling the sandbox, and I was able to get to all the logs (which is good) but according to this page: https://developer.apple.com/documentation/security/app_sandbox/ it says: To distribute a macOS app through the Mac App Store, you must enable the App Sandbox capability Since we are planning on distributing our app on the store, this presents a big problem for me. (I didn't try submitting to TestFlight to see if it's really the case). I don’t know if there are exclusions or ways around this – I don’t see an entitlement that I can add which would allow access to the logs. Does anyone know a way around this? Thanks, David
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609
Jan ’24
Cannot switch log level to off?
What do I miss here? root@MacBook-Pro /tmp # sw_vers ProductName: macOS ProductVersion: 13.6.1 BuildVersion: 22G313 root@MacBook-Pro /tmp # log config --mode "level: off" root@MacBook-Pro /tmp # log config --status System mode = INFO root@MacBook-Pro /tmp # log config --mode "level: debug" root@MacBook-Pro /tmp # log config --status System mode = DEBUG root@MacBook-Pro /tmp # log config --mode "level: off" root@MacBook-Pro /tmp # log config --status System mode = DEBUG
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502
Jan ’24
/usr/bin/log sometimes does not work through NSTask
Our application (which happens to run in an admin account, thus there's no problem authenticating) collects logs calling /usr/bin/log through NSTask. Usually this works all right, but sometimes all we get is the header Timestamp Thread Type Activity PID TTL and nothing else. The tool finishes with a zero result code, we get nothing on stderr and just the header above on stdout, with a proper EOF (as determined by a zero-length availableData read from an NSFileHandle through the stdout pipe). At the same moment, if the /usr/bin/log tool is run manually in a Terminal window with precisely the same arguments in the same user account the application runs in, we get the logs all right. Any idea what might be the culprit and how to fix the problem? Thanks!
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454
Jan ’24