Delve into the world of built-in app and system services available to developers. Discuss leveraging these services to enhance your app's functionality and user experience.

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Performance Implications of XPC polling
On my MAC, I have a XPC server running as a daemon. It also checks the clients for codesigning requirements. I have multiple clients(2 or more). Each of these clients periodically(say 5 seconds) poll the XPC server to ask for a particular data. I want to understand how the performance of my MAC will be affected when multiple XPC clients keep polling a XPC server.
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Feb ’25
How to learn most recent best practices?
Hello. Background: Most learning resources are for leaning Swift/Objective-C. I'm pretty sure I need something different. I'm already an experienced software engineer, just new to iOS/MacOS development. My problem is not learning the language, but rather how to learn modern best practices. I cannot find examples for what I'm looking for. So much seems to be sparse on implementation details, out of date, or both. I'm trying to write an app that has a few distinct parts. The UI portion will be mostly a menu bar app, which I am not having a problem discovering resources for how to implement. The app will also have a daemon and utilize network extensions. This is where I am having trouble. What's the current best practices on how to write and launch a daemon? Should the daemon be its own library/package which is them imported into the main app? If so, which Xcode template do I use for this? Are there any Hello World! examples of this? What is the best way for a UI app to communicate with a daemon? Are there any Hello World! repositories on how to implement network extensions? Should this be done in the main UI app, or in a separate library/package? TIA
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149
Apr ’25
Problem setting up AASA file (paths with queries)
In a project having both an app and a website, the following two website urls are to be handed over to the corresponding app: https://www.example.com/search?plus https://www.example.com/search?query=something In AASA file, this becomes: "components": [ { "/": "/search", "?": { "plus": "", "query": "?*" } } However, finally it does not work for both urls. Only the one with "query" works by hand over to app. For investigation, I have tried this for the problematic link: "components": [ { "/": "/search", "?": "plus" } and this works. How can I get both to work? (note that for the sake of brevity, only a portion of the AASA files are shown)
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181
May ’25
Error while validating the mobile app
The errors below pop up when I validate or distribute the mobile app; this error happens with the upgraded Xcode version. I have Xcode 16.2, and the minimum target deployment is 14.0. Please help me to resolve these errors. build was successful, I can launch my application from the simulator Validation failed Invalid Bundle. The bundle .app/Frameworks/hermes.framework does not support the minimum OS Version specified in the Info.plist. (ID: ee79350d-249e-4101-89fe-e41b2620f4d6) Validation failed Missing Info.plist value. A value for the key 'MinimumOSVersion' in bundle .app/Frameworks/hermes.framework is required. (ID: b0f58cd5-2c72-437b-98c9-1b2b4122c203) Validation failed Invalid MinimumOSVersion. Apps that only support 64-bit devices must specify a deployment target of 8.0 or later. MinimumOSVersion in ‘.app/Frameworks/hermes.framework' is ''. (ID: c2a6247f-21d6-438f-b52f-572425b7aa65)
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332
Feb ’25
CardSession.Error.maxSessionDurationReached not thrown on iOS 26
Hello, I have an app that emulates an NFC card using NFC HCE. Since yesterday I saw an increasing number of crashes on iOS 26 only, which wasn't there before. From what I can see, it seems the app crashes when the NFC presentment intent is shown and 60 seconds passed and user does nothing. The app just crashes after 60 seconds. On previous iOS versions, I know that CardSession.Error.maxSessionDurationReached was thrown after 60 seconds. Is something changed in iOS 26?
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187
Sep ’25
iOS Message Filter Extension - deferQueryRequestToNetwork(completion:) error
iOS Message Filter Extension - deferQueryRequestToNetwork(completion:) error I made a test app using the iOS App template and added a target using the Message Filter Extension template which invokes deferQueryRequestToNetwork(completion:) when receiving an SMS. The app and the extension have same "Associated Domains Capabilities" with "messagefilter" pointing to a server which receives query requests and returns proper responses. The extension has the "ILMessageFilterExtensionNetworkURL" key in Info.plist file which specifies the server URL. deferQueryRequestToNetwork(completion:) throws a com.apple.calls.messagefilter error which reads "Extension's containing app (appID ) unauthorized to defer requests to host "
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678
Sep ’25
Receive Custom URL Parameters
Hello! I’m trying to handle custom URLs (e.g., customurl://open?param=value) that open the app. However, while the app launches via the custom URL as expected, the parameters are not being passed to or are accessible from the iOS-specific implementation. Currently, if I open a custom URL via Safari, the app gets launched but the custom URL and parameters are not accessible. customurl://open?hello=test According to the iOS Docs ( https://developer.apple.com/documentation/xcode/defining-a-custom-url-scheme-for-your-app#Handle-incoming-URLs ) any URLs should be passed to: func application(_ application: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:] ) -> Bool I do not register the above application function to be called but instead this one is executed during app start with launchOptions always being nil: func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool This is the case regardless of if the App is started fresh or was already running in the background. My pInfo entry for the custom URL: <key>CFBundleURLTypes</key> <array> <dict> <key>CFBundleTypeRole</key> <string>Viewer</string> <key>CFBundleURLName</key> <string>dev.customurl.project</string> <key>CFBundleURLSchemes</key> <array> <string>customurl</string> </array> </dict> <dict/> </array> TLDR: How can I access the parameters, passed with the URL? Any thoughts on what I am doing wrong?
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Apr ’25
CallKit Call Blocking Not Working
I have also tested this on iOS 26 (Beta 9 and above), and the CallKit call blocking functionality is not working. Numbers that should be blocked still ring through. Caller Identification continues to function as expected, but blocking entries (addBlockingEntry) are ignored.
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262
Sep ’25
Live Caller ID: Multiple userIdentifier values for same device - Expected behavior?
Hello! We're currently testing Live Caller ID implementation and noticed an issue with userIdentifier values in our database. Initially, we expected to have approximately 100 records (one per user), but the database grew to about 10,000 evaluationKey entries. Upon investigation, we discovered that the userIdentifier (extracted from "User-Identifier" header) for the same device remains constant throughout a day but changes after a few days. We store these evaluation keys using a composite key pattern "userIdentifier/configHash". All these entries have the same configHash but different userIdentifier values. This behavior leads to unnecessary database growth as new entries are created for the same users with different userIdentifier values. Could you please clarify: Is this the expected behavior for userIdentifier to change over time? If yes, is there a specific TTL (time-to-live) for userIdentifier? If this is not intended, could this be a potential iOS bug? This information would help us optimize our database storage and implement proper cleanup procedures. Thank you for your assistance!
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Mar ’25
iOS 26.2 (23C55): DeviceActivity eventDidReachThreshold fires with 0 Screen Time minutes
On iOS 26.2 (23C55), DeviceActivityMonitor.eventDidReachThreshold fires intermittently for a daily schedule (00:00–23:59) even when iOS Screen Time shows 0 minutes for the selected apps that day. This causes premature shielding via ManagedSettings. Environment: iPhone 13 Pro Max, iOS 26.2 (23C55). Event selection: 2 apps. Threshold: 30 minutes. Multiple TestFlight users report the same behavior across various app selections and thresholds. Intermittent (~50% of days); sometimes multiple days in a row. Not observed in testing prior to iOS 26.2. Evidence: sysdiagnose + Screen Time screenshots (with 0 screen time on selected apps) + unified logs show UsageTrackingAgent notifying the extension that “unproductive from activity daily reached its threshold,” followed immediately by ManagedSettings shield being applied (extension reacting to the callback). Filed Feedback Assistant: FB21450954. Questions: Are others seeing this on 26.2? Does it correlate with restarting monitoring at interval boundaries or includesPastActivity settings?
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2w
Message Filter Extension won't use Basic Auth
I am trying to set up a message filter extension that will use shared web credentials for basic auth when calling to its ILMessageFilterExtensionNetworkURL. I have associated domains set up for both "messagefilter:" and "webcredentials:" and the message filter IS correctly calling the ILMessageFilterExtensionNetworkURL with each message - so that part is working. As detailed here, I have set up Shared Web Credentials and my view controller is using SecAddSharedWebCredential() to save the creds to the correct domain. Using Authorization services, the creds are auto-filled into my app's login screen. When I go under Settings > Passwords, I see the creds are saved and they are the correct creds to the corrent website that matches ILMessageFilterExtensionNetworkURL. Regardless of all of this, the deferQueryRequestToNetwork() refuses to use the creds and implement Basic Auth in its URL call. It makes the call to the correct URL, it just won't use the Shared Web Creds for basic auth. Any help would be greatly appreciated.
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2w
Shape detection for other apps?
When selecting a stroke path for object on PKCanvas, the option "Snap to Shape" appears. I understand this function is still in beta and has not made available natively to other PencilKit app. Is there a way using Stroke API to call this function directly after the user hold pencil for half a second when stroke is done drawing, just like how it behaves in native apps?
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2.4k
3w
Tahoe 26.2 breaks printing with PaperCut
Issue After upgrading to Tahoe 26.2, print queues monitored by PaperCut no longer work. The print queue gets paused, and the jobs fail to print. This issue was discovered during our internal testing prior to the Tahoe 26.2 public release, and a growing number of our mutual customers have also reported it since then. Root cause This appears to be due to changes in the behavior of CUPS Sandbox restrictions, which prevent the backend (and filter) from reading/writing to the PaperCut install folder. Error messages From syslog. 2025-12-22 16:41:59.283761+1100 0x1daf61 Error 0x0 0 0 kernel: (Sandbox) Sandbox: papercut(5783) deny(1) file-write-data /Library/Printers/PaperCut/Print Provider/print-provider.log When trying to create a TCP socket from the PaperCut filter. 2025-12-15 19:50:08,403 ERROR: os_tcp_socket_create: getaddrinfo failed: nodename nor servname provided, or not known Technical details PaperCut implements print queue monitoring using a CUPS backend (and filter). CUPS backends and filters run in a security 'sandbox' which limits what they can do (such as file/folder access, create network sockets, and execute sub-processes, etc.). The PaperCut backend (and filter) relies on some of these operations, so to function correctly, our code updates /etc/cups/cups-files.conf with "Sandboxing relaxed". Until 26.2, this relaxed mode allowed us to read/write to PaperCut folders, create TCP sockets to communicate with the local PaperCut Application Server, and execute/kill sub-processes. As an alternative to the relaxed mode, we also tried "Sandboxing off", but that doesn't help either (from CUPS scheduler/conf.h). typedef enum { CUPSD_SANDBOXING_OFF, /* No sandboxing */ CUPSD_SANDBOXING_RELAXED, /* Relaxed sandboxing */ CUPSD_SANDBOXING_STRICT /* Strict sandboxing */ } cupsd_sandboxing_t; Test code We can provide a simplified version of our backend that demonstrates the issue if required Questions Has the CUPS sandbox relaxing changed? According to the CUPS man pages (cups-files.conf(5)), "Sandboxing relaxed" should still work as before. If this is the new intended behavior, what are the other options/directives we can use to relax the limitations on CUPS backends and filters?
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3w
After unholding CallKit, the audio does not restore.
In my application, I use CallKit and have supportsHolding = true set. During my phone call, another call comes in (e.g., GSM). I accept the incoming call and put the current call on hold. If I end the active call myself, everything is fine, and CallKit calls the method provider(_ provider: CXProvider, didActivate audioSession: AVAudioSession). However, if the other party ends the call, the second call remains on hold. In the application, the user clicks on unhold, and I notify CallKit that the hold has ended. But in this case, the didActivate method is not called at all. If I try to activate the audio myself after unhold, I receive the error: Domain=NSOSStatusErrorDomain Code=561017449 "Session activation failed" UserInfo={NSLocalizedDescription=Session activation failed} AVAudioSessionErrorInsufficientPriority == NSOSStatusErrorDomain Code: 561017449 What needs to be done for CallKit to activate my audio?
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1.6k
Jan ’26
WatchOS app not downloaded from appstore
This is a bit of a headscratcher. Xcode 16 fyi. I've written a standalone watchos app (with a stub ios app). Distributes and works perfectly over Testflight. I've submitted for app store and it passed the checks an I've released it for sale. Told my brother to use a promo code to download it and show me how it looks and report me any nuisances. He tells me there's no app neither on phone (expected) nor in watch. And he checked both the Watch ios app list and the watch. I've gone through various GPTs and they've all told me the basic troubleshooting. That his watch might not be supported (wrong, it's a watch 10 ultra with latest updates and my min supported versions are hilariously low). They've suggested that I might not have the right keys for making it standalone set, also no. They suggested that skip_install shouldn't be set to no; also wrong I think they're thinking xcode 13 and below. The stub ios app has a dependency on watchos app and also has an embed directive. I also checked the archive and saw the watchos app embedded indeed. Again, the app works perfectly fine when distributed over testflight. And AFAIK that's a release build which I know for a fact because I had a problem with not giving healthkit entitlements to release (that was another but minor headscratcher at the time, when it was working over direct xcode upload). Minor detail, I've written, test(flight)ed the app in UK and in English, my brother is in Turkey. Of course now I immediately pulled the app out of sale because I don't want people paying and getting nothing, that's gonna cause a lot of trouble. So I need any help I can get to How to debug this without exposing the app and myself: is it possible to limit the release? Obviously: what could be going wrong? How the hell did I even pass app review? Is this maybe isolated to my brother's watch? I'm more than happy to share project files and/or info.plist files(end products of them, because my plists are generated from project file).
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Apr ’25
Methods for dealing with macOS Wallpaper Cache
Hello, Back in January 2024, I filed a bug report regarding a cache being kept by the macOS Wallpaper Agent. This cache contains every image ever set as a users wallpaper, and at the time the issue was reported, it never cleared, leaving hundreds of gigabytes wasted on users disks in some cases. FB13536275 This issue was ultimately fixed in macOS 15.1 beta 6, and remained fixed for the duration of macOS 15. The fix was excellent - the cache was reduced to storing just 2-3 days worth of images. Sadly, we've discovered that this issue is back in macOS Tahoe. The cache has moved locations, and once again is not clearing. We have filed this bug again, less than a year after it was first fixed: FB20636593 We develop an app called 24 Hour Wallpaper that keeps the wallpaper in sync with the time of day. This necessitates that the app regularly changes the wallpaper, which sadly now results in an infinitely growing and useless cache of BMP files generated by the system. As we waited 10 months for this to get fixed the first time, we expect to wait at least that long to get it fixed again, and have no confidence that it will stay fixed because the last fix lasted less than a year. This leaves us in a bad position, as people can't use our app without the cache growing arbitrarily and ultimately completely filling their disk. We've already had customers call Apple to complain about this, and the good news is that the support agents understand that this is a problem with macOS, not with our app. What we've decided to do is add a feature to the app that monitors the size of this cache and periodically deletes it. We're required to get the users permission the first time to do this, but after that the permission is cached, so the app can keep the cache folder clean regardless of if macOS is doing it's job or not. We haven't seen any side effects or problems as a result of doing this. We've seen other apps like CleanMyMac do this without any problems. We're wondering if there is anything we should be aware of regarding this caches behavior before releasing this flushing feature. Thanks for your time, -josh
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4w
WeatherKit API inaccessible for some users
Hi All, I’m puzzled by this issue: my app uses WeatherKit to fetch hourly UV-index and temperature forecasts. The same build, running on the latest iOS, succeeds on most devices but consistently fails on a few. Strangely, the paired Apple Watch version retrieves the data without problems. Could WeatherKit be applying per-user throttling? Any insight would be greatly appreciated.
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Jun ’25