Keychain access on watchOS 2 not working on the actual watch - ios

I have read in the Apple developer forum that unlike watchOS 1, watchOS 2 does not share its keychain with the phone app so bam!! keychain sharing is not enabled by default we got to do a workaround for that.
Ok coming to my issue, I was trying to run a very basic keychain access program on the actual watch device running the latest beta (beta4) using a git library https://github.com/jrendel/SwiftKeychainWrapper
let saveSuccessful: Bool = KeychainWrapper.setString("keychainData", forKey: "ImportantKeychainData")
if saveSuccessful{
let retrievedString: String? = KeychainWrapper.stringForKey("ImportantKeychainData")
print(retrievedString)
}
else
{
print("unable to write keychain data")
}
On the simulator it works like a charm but when I try to run the same on the actual watch it gives me an status code of -34018
There was no public documentation about this error code but I did a little digging to find out it turned out to be
errSecMissingEntitlement = -34018, /* Internal error when a required entitlement isn't present. */
source: http://opensource.apple.com/source/Security/Security-55471/sec/Security/SecBasePriv.h
I did a lot of research actually a full day on this and people pointed me to various directions, like memory issues, entitlements, profile issue, bug in keychain etc.
The catch here is that most of the dev's who reported this issue did not have it continuously like I got it on every run of the app, they had it at certain places only like when app was in background etc. To summarise,
1. I tried the same piece of code on iOS 9 beta 4 and it worked well on the phone.
2. The same code works well on the watch simulator.
3. The same code does not work on watchOS beta 4 returns -34018 continuously on the device but works well on the simulator.
4. All this testing is done using free provisioning introduced from Xcode 7, entitlements were added to the phone app and the watch extension, keychain sharing was enabled, app groups was enabled.
My questions are
1. Am I missing something here that I have to do with the device keychain that I am supposedly doing it wrong?
2. Is there an issue with free provisioning?
3. Is there an issue with the keychain perhaps??
Any help is appreciated.
FYI I also tried Apple's KeychainItemWrapper, customs code directly talking to SecItem methods nothing turned out to be fruitful.
Update, I tried this as well it fails as usual
let storableString:NSString = "keychain in watchos is working with simple code"
let query : [NSString : AnyObject] = [
kSecClass : kSecClassGenericPassword,
kSecAttrService : "WatchService",
kSecAttrLabel : "KeychainData",
kSecAttrAccount : "SecureData",
kSecValueData : storableString.dataUsingEncoding(NSUTF8StringEncoding)!
]
let result = SecItemAdd(query, nil)
print(result)
Update 2: Issue has been fixed in watchOS2 beta 5.

Issue has been fixed by Apple in the recent watchOS 2 beta 5.

Related

Requesting an In App Purchase in iOS 13 fails

I use SwiftyStoreKit to request In App Purchases and get only this error with iOS 13:
Error: Optional(Error Domain=ASDErrorDomain Code=507 "Error decoding object" UserInfo={NSLocalizedDescription=Error decoding object, NSLocalizedFailureReason=Attempted to decode store response})
I cannot request information about the products, nor make purchases with a sand box account. However, it works fine in iOS 12.1 on my device. It does not work with the iPhone 11 simulator or an actual device with iOS 13.
I have found a lot, that the Xcode 11 GM seed 1 beta simulator had this problem, but have not found a solution yet. I also tested it with the new released Xcode 11 GM seed 2 version, but there was no fix for me.
Does anyone have a solution on how I can request and purchase In App Purchases again with iOS 13 installed?
Restarting Xcode and simulator did the trick: now my in-app purchases load properly in iOS 13 simulator.
EDIT: This happens in release Xcode 11 too. And happens once in a while, but restarting Xcode and simulators still helps.
EDIT 2: In Xcode 12 beta this bug is also present. But the solution is to create new StoreKit Configuration file (in File -> New menu)
Then add all your products there. Use the same product id's as in AppStore Connect.
Then add this file to Run Scheme configuration.
I had the same issue, iOS13 Simulators produced the same error, iOS12 Simulators were working well.
I then tried out on the iPhone with iOS13 installed, there the calls were working flawlessly too.
Hoping that it'll be fixed soon in Xcode Simulators, I guess until then we are stuck with the error.
Edit:
Now it seems to work also in iOS 13 Simulator Devices.
Note: I've updated the answer, read the Edit part.
To share my experience, it seems that this problem does not exist any more in Xcode 11.1 GM Seed. There's no need to restart Simulators or Xcode to make in-app purchases work anymore.
I had submitted an app for review and it was rejected because of that particular error. As it turns out, it was rejected for a stupid reason as it wasn't my app's bug, however I spent hours trying to get around it.
So, just update to Xcode 11.1 GM Seed and run again. Everything will be okay.
EDIT
The issue still exists in Xcode 11.1 and apparently I was just lucky that it didn't happen to me again. However, I had a second rejection for the exact same reason. What eventually worked and made my app get approved was this:
I had to update my IAP record on App Store by editing and saving it again.
So, I recommend you to try the same; change something temporarily in your IAPs, save and then revert your changes (and save again) so records on the App Store to be refreshed.
FYI, after the second rejection Apple invalidated my IAP and therefore showed me the way. It looks like to be a known issue to them at the end.
For details read this discussion I wrote on Reddit.
For those that has this issue in iOS 14.0, you still need to create the storekit configuration file as per #silvansky answer. Rather than adding it to the target, we can actully start an SKTestSession before making any product request in order to avoid the error.
if #available(iOS 14.0, *) {
do {
let session = try SKTestSession(configurationFileNamed: "Your_StoreKit_Configuration_File_Name")
session.disableDialogs = true
} catch {
// catch error here
}
// Start your product request here
let productIdentifiers = Set(["product_identifier_1", "product_identifier_2"])
let productsRequest = SKProductsRequest(productIdentifiers: productIdentifiers)
productsRequest.delegate = self
// Run the request
productsRequest.start()
}
You can refer to Apple's documentation for SKTestSession for more info: https://developer.apple.com/documentation/storekittest/sktestsession

Keychain returned the following status: -34018 [duplicate]

Sometimes when I run an application on device from Xcode I would try to access the keychain but fail due to error -34018. This doesn't match any of the documented keychain error codes and can't be consistently reproduced. (happens maybe 30% of the time, and it's not clear to me why it happens). What makes debugging this problem very difficult is the total lack of documentation. Any idea what causes this and how to fix it? I'm using Xcode 5 and running iOS 7.0.4 on device.
There is an open issue about this here: https://github.com/soffes/sskeychain/issues/52
EDIT: Adding keychain access code per request
I'm using the SSKeychain library for interfacing with keychain. Here's the snippet.
#define SERVICE #"default"
#implementation SSKeychain (EXT)
+ (void)setValue:(NSString *)value forKey:(NSString *)key {
NSError *error = nil;
BOOL success = NO;
if (value) {
success = [self setPassword:value forService:SERVICE account:key error:&error];
} else {
success = [self deletePasswordForService:SERVICE account:key error:&error];
}
NSAssert(success, #"Unable to set keychain value %# for key %# error %#", value, key, error);
if (!success) {
LogError(#"Unable to set value to keychain %#", error);
}
LogTrace(#"Will set keychain account %#. is to nil? %d", key, value == nil);
if (value == nil)
LogWarn(#"Setting keychain %# to nil!!!", key);
}
+ (NSString *)valueForKey:(NSString *)key {
NSError *error = nil;
NSString *value = [self passwordForService:SERVICE account:key error:&error];
if (error && error.code != errSecItemNotFound) {
NSAssert(!error, #"Unable to retrieve keychain value for key %# error %#", key, error);
LogError(#"Unable to retrieve keychain value for key %# error %#", key, error);
}
return value;
}
+ (BOOL)removeAllValues {
LogInfo(#"Completely Reseting Keychain");
return [[self accountsForService:SERVICE] all:^BOOL(NSDictionary *accountInfo) {
return [self deletePasswordForService:SERVICE account:accountInfo[#"acct"]];
}];
}
#end
Vast majority of the time it's just fine. Sometimes I'll hit the assertion failures where I'm unable to either write to or read from keychain, causing critical assertion failure.
iOS 10 / XCode 8 Fix:
Add KeyChain Entitlement, Go to project
settings->Capabilities->Keychain Sharing->Add Keychain Groups+Turn On
An answer here, from Apple:
UPDATE: We have finally been able to reproduce the -34018 error on iOS
8.3. This is the first step in identifying the root cause and then coming up with a fix.
As usual, we can't commit to a release timeframe, but this has
affected many developers and we really want to get this resolved.
Earlier I suggested adding a small delay in
application:didFinishLaunchingWithOptions and
applicationDidBecomeActive: before accessing the keychain as a
workaround. However, that doesn't actually appear to help. That means
that there's no known workaround at this time other than relaunching
the app.
The issue appears to be related to memory pressure, so perhaps being
more aggressive in handling memory warnings may alleviate the problem
https://forums.developer.apple.com/thread/4743#14441
UPDATE
OK, here’s the latest.
This is a complex problem with multiple
possible causes:
Some instances of the problem are caused by incorrect
app signing. You can easily distinguish this case because the problem
is 100% reproducible.
Some instances of the problem are caused by a
bug in how iOS supports app development (r. 23,991,853). Debugging
this was complicated by the fact that another bug in the OS (r.
23,770,418) masked its effect, meaning the problem only cropped up
when the device was under memory pressure. We believe these problems
were resolved in iOS 9.3.
We suspect that there may be yet more causes
of this problem.
So, if you see this problem on a user device (one
that hasn’t been talked to by Xcode) that’s running iOS 9.3 or later,
please do file a bug report about it. Try to include the device
system log in your bug report (I realise that can be tricky when
dealing with customer devices; one option is to ask the customer to
install Apple Configurator, which lets them view the system log). And
if you do file a bug, please post your bug number, just for the
record.
On behalf of Apple I’d like to thank everyone for their
efforts in helping to track down this rather horrid issue. Share and
Enjoy
https://forums.developer.apple.com/thread/4743#126088
Basically you have to codesign your .xcttest folder by adding the following as a run script in your test target.
codesign --verify --force --sign "$CODE_SIGN_IDENTITY" "$CODESIGNING_FOLDER_PATH"
I got a lot of -34018 errors when testing my keychain on the device and this managed to fix it.
If the problem does not exist in your test target this is probably not the solution.
After inspecting the source code. I have noticed that the keychain features are accessed through a security daemon that runs in its own process (separated from the app process).
Your app and the securityd process 'talk' together through a technology called XPC.
If necessary, the securityd is launched via the well-known launchd command by XPC. You can probably check that the daemon is running in the Activity Monitor App (if running in Simulator of course) and that its parent process is launchd.
My guess here is that it is possible that for any unknown reason the security daemon fails to start or do it too slowly and is not ready when you try to use it.
Maybe you could think on how to pre-launch the daemon.
I apologize for not being more precise. I hope it could help you to go a bite further in your investigations.
I’m observing similar behavior after building and running my code in Xcode 6 beta with iOS 8 SDK (it’s working correctly with Xcode 5 / iOS 7). In Xcode 6, in iOS Simulator SecItemCopyMatching always returns -34018. It started working after turning on the “Keychain Sharing” in Capabilities tab.
However I have another issue. I’m developing static library, that is used by (among others) Demo application. The above solution works for Demo application project, but when I try to unit test my static library project, I have exactly the same error. And the problem is that my static library project doesn’t have the Capabilities tab (as it’s not the standalone application).
I’ve tried the solution posted here by JorgeDeCorte, with codesigning in the test target, but it doesn’t work for me.
Try disabling all breakpoints when launching the app from Xcode.
You can enable them afterwards.
(None of the above workarounds worked for me)
I just had the same issue on the simulator running 7.1 & 8.0. While doing some digging, I noticed that the Apple sample app had KeyChain Sharing turned on for its target capabilities. I turned it on for my app which resulted in creating an entitlement file that I left with the default values and now I am not getting anymore -34018 errors. This is not ideal but I will live the KeyChain sharing option for now.
Codesigning a .xctest bundle isn't as easy as it sounds in some cases. Principally JorgeDeCorte is right with his answer that the given short line as a Run Script is enough for most of the devs.
codesign --verify --force --sign "$CODE_SIGN_IDENTITY" "$CODESIGNING_FOLDER_PATH"
But when you have multiple certificates in your keychain this will fail with the following line
iPhone Developer: ambiguous (matches "iPhone Developer: Your Name (ABC123DEF45)" and "iPhone Developer: Your Name (123ABC456DE)"
A solution to get the right certificate even with multiple ones is this short script. For sure this is not ideal, but as of my knowledge you have no chance to get the certificate that Xcode found and uses for signing your .app.
echo "codesign --verify --force --sign \"$CODE_SIGN_IDENTITY\" \"$CODESIGNING_FOLDER_PATH\""
IDENTITIES=`security find-identity -v -s "Code Signing" | grep "iPhone Developer" | awk '{ print $2 }'`
for SHA in $IDENTITIES; do
codesign --verify --force --sign $SHA "$CODESIGNING_FOLDER_PATH"
if [ $? -eq 0 ]; then
echo "Matching identity found: $SHA"
exit 0
fi
done;
exit 1
I got bitten by this, too and had no success with any of the other workarounds.
I then cleaned up my provisioning profiles on the devices itself by deleting all of them related to my app as well as all the wildcard profiles (this seems to be the point).
To do this, go to the "Devices" Window in Xcode and right-click your (connected) phone:
Click on "Show provisioning profiles" and delete the related ones, and especially the team profiles:
including the ones with the asterisk.
After reinstallation the app, everything went back to normal.
I have fixed this problem (I think). I had a wildcard provisioning profile on my device that showed it did not have a valid signing identity. I also had a provisioning profile for my app that was valid. When I deleted the wildcard profile, I stopped getting the -34018 errors.
I also made sure that the code signing identity and provisioning profile listed in the Code Signing section of the Build Settings of the target were identical to the one for the app (not the generic "iPhone Developer" one)
I was getting -34018 error in my app (iOS 8.4) very rarely. After some investigation I've found that this issue occurs when the app requests data from keychain too often.
For example, in my situation it was two read requests for one specific key at the same time from different application modules.
To fix that I've just added caching this value in memory
I was having the same problem, out of the blue, running on a test device with Xcode 6.2, iPhone 6, iOS 8.3. To be clear, this was not experienced while running Xcode tests, but rather while running the actual app on my device. In the simulator it was fine, and running on the app itself it had been perfectly fine until recently.
I tried all of the suggestions I could find here, such as removing the provisioning profiles on my device (I removed ALL of them), temporarily enabling the Keychain Sharing capability in my project (even though we don't really need that), making sure my development account in Xcode was totally refreshed with all of the certificates and provisioning profiles, etc. Nothing helped.
Then I temporarily changed the accessibility level from kSecAttrAccessibleAfterFirstUnlock to kSecAttrAccessibleAlwaysThisDeviceOnly, ran the app, and it worked fine and was able to write to the Keychain. Then I changed it back to kSecAttrAccessibleAfterFirstUnlock, and the problem seems to have gone away "permanently."
Just got bitten by this bug on Xcode 8 Beta 3. Turning on Keychain Sharing seems to be the only solution.
I had the same issue. Fixed it by setting up Keychain Sharing.
(this is not a direct answer to the OP's question, but might help others)
Started getting the keychain error -34018 consistently in simulator after updating Xcode from version 7.3.1 to 8.0.
Following this tip from daidai's answer,
Some instances of the problem are caused by incorrect app signing. You can easily distinguish this case because the problem is 100% reproducible.
it was discovered that Provisioning Profile had somehow been set to None in the Signing sections of the target.
However, setting the Provisioning Profile fields to valid values was not sufficient to resolve the issue in this case.
Further investigation showed that the Push Notifications entitlement also displayed an error. It said the "Add the Push Notifications feature to your App ID." step was completed, but step "Add the Push Notifications entitlement to your entitlements file" was not.
After pressing "Fix Issue" to fix the Push Notification issue, the keychain error was resolved.
For this particular target, the "Keychain Sharing" entitlement had already been turned on at some previous time. Turning it off has not caused the keychain error to reappear so far, so its not clear whether it is necessary in this case.
In iOS 9 I turned off Address Sanitizer and it started working on the device.
The only solution that worked for me was first storing nil for the specified key, and then storing my new value with a separate operation. It would fail due to error -34018 if I attempted to overwrite the existing value. But as long as I stored nil first, then the updated value would be stored successfully immediately afterwards.
I met this -34018 issue today when running SecItemDelete API.
What I did to fix this is:
1. Following #k1th solution https://stackoverflow.com/a/33085955/889892
2. Run the SecItemDelete in main thread(Previously it's read from main thread, so just align this with deleting).
Sorry it comes back again :(
Turn on Keychain sharing in your project's capabilities, it should solve the problem.
What worked for me
Turn on Keychain Sharing.
Use the keychain as less as possible and cache the data in memory, UserPreferences, disk, etc.
Retry many times the keychain CRUD operations if these failed.
Use DispatchQueue.sync for storing/deleting/updating the data.
For me it was an app signing issue. I simply switched to the correct signing team in Xcode and the error no longer occurred

Keychain error -34018, unable to delete current dictionary

I have an app that is written in Swift 2.3. The app uses the KeychainItemWrapper that makes accessing the Keychain simpler.
When I run the app in the iOS 9.3 simulator with Xcode, the app runs as expected and there are no issues reading/writing to the keychain.
The same exact app, without any changes in my code, crashes with the call to:
- (void)resetKeychainItem
With the line:
SecItemDelete((__bridge CFDictionaryRef)tempDictionary);
Thus making this NSAssert give me my error:
NSAssert( junk == noErr || junk == errSecItemNotFound, #"Problem deleting current dictionary." );
Researching this error by the code 34018 pointed me to other posts with users experiencing a bug with the keychain that was actually brought to the attention of the devs at Apple. It was made a high priority bug, and one post suggested iOS 9.3 had a fix for this (my app works on iOS 9.3!).
However, it is my understanding that Xcode 8 handles such things as code signing differently than previous versions. So I wonder if with iOS 10 if this is a possible new bug.
If anyone has any ideas or experience with this error on iOS 10/Xcode 8... please share your suggestions.

iOS Keychain writing value results in error code -34018

I have an iOS application that stores some sensitive information in the keychain.
While writing values into the keychain, I am getting error code -34018.
I am currently using Apple's iOS KeyChainItemWrapper class.
Both of the following lines of code receive the same error code.
OSStatus res1 = SecItemCopyMatching((__bridge CFDictionaryRef)genericPasswordQuery, (CFTypeRef *)&attributes);
OSStatus res = SecItemUpdate((__bridge CFDictionaryRef)updateItem, (__bridge CFDictionaryRef)tempCheck);
This issue does not occur every time, but intermittently. Once I get this error, I am no longer able to write any values to the keychain.
I have printed the error description like so:
NSError *error = [NSError errorWithDomain:NSOSStatusErrorDomain code:res userInfo:nil];
and this is what the error prints out:
Error: Error Domain=NSOSStatusErrorDomain Code=-34018 "The operation couldn’t be completed. (OSStatus error -34018.)"
Seems like this is a bug in Keychain, which only appears when you launch your app from xcode. See here: https://github.com/soffes/sskeychain/issues/52
We debugged it a lot and it seems an issue accessing the keychain when
the app is launched from the background. This is only happening with
the debugger (i.e. when launched from Xcode). We think the issue
might be related in our case to the debugger keeping alive the app
even if it should be killed by the OS. We tried in fact to run the
app and then put it in background and launch many other app to occupy
RAM. With the debugger the bug came up when resuming the app from the
background, while without the debugger it didn't (we did run at least
10 tests each).
If someone will come here back with this error and XCode8 with iOS10, probably you have to enable KeyChain Share in the tab Capabilities:
As others have mentioned, this is a Keychain bug, one that Apple is aware of and has been aware of since at least mid-2015.
As of March 22, 2016, however, Apple has said:
We believe these problems were resolved in iOS 9.3.
iOS 9.3 was released on March 21, 2016.
See the thread: https://forums.developer.apple.com/thread/4743
To quote the response by an Apple employee:
Mar 22, 2016 3:28 AM
OK, here’s the latest. This is a complex problem with multiple possible causes:
Some instances of the problem are caused by incorrect app signing. You can easily distinguish this case because the problem is 100% reproducible.
Some instances of the problem are caused by a bug in how iOS supports app development (r. 23,991,853). Debugging this was complicated by the fact that another bug in the OS (r. 23,770,418) masked its effect, meaning the problem only cropped up when the device was under memory pressure.
We believe these problems were resolved in iOS 9.3.
We suspect that there may be yet more causes of this problem.
So, if you see this problem on a user device (one that hasn’t been talked to by Xcode) that’s running iOS 9.3 or later, please do file a bug report about it. Try to include the device system log in your bug report (I realise that can be tricky when dealing with customer devices; one option is to ask the customer to install Apple Configurator, which lets them view the system log). And if you do file a bug, please post your bug number, just for the record.
On behalf of Apple I’d like to thank everyone for their efforts in helping to track down this rather horrid issue.
Share and Enjoy
This held me up for 2 hours before I found a quick "fix" - reboot the iOS device
A quote from the discussion at http://forums.developer.apple.com/thread/4743,
From user littledetails
As others have reported, this mysterious keychain error is most easily observable when launching via Xcode with the debugger attached. Once the error starts occurring, the keychain doesn't seem to right itself regardless of memory pressure until one reboots the device.
When I rebooted my device the error went away, allowing me to continue testing. Not sure what else to do. In my situation, moving to NSUserDefaults or some other storage solution was not a possibility.
One way to get around this issue with the keychain is to use dispatch_async to allow the app to launch. This works when the app is opened from the background. Also make sure you have the kSecAttrAccessibleAfterFirstUnlock accessibility setting on the keychain.
dispatch_async(dispatch_get_main_queue(), ^{
// save/write to keychain
})
I am using GenericKeychain classes from apple:
https://developer.apple.com/library/content/samplecode/GenericKeychain/Introduction/Intro.html#//apple_ref/doc/uid/DTS40007797-Intro-DontLinkElementID_2
struct KeychainConfiguration {
static let serviceName = "MyAppService"
/*
Specifying an access group to use with `KeychainPasswordItem` instances will create items shared accross both apps.
For information on App ID prefixes, see:
https://developer.apple.com/library/ios/documentation/General/Conceptual/DevPedia-CocoaCore/AppID.html
and:
https://developer.apple.com/library/ios/technotes/tn2311/_index.html
*/
// static let accessGroup = "[YOUR APP ID PREFIX].com.example.apple-samplecode.GenericKeychainShared"
/*
Not specifying an access group to use with `KeychainPasswordItem` instances
will create items specific to each app.
*/
static let accessGroup: String? = nil
}
In this file I was specifying my custom accessGroup in this line static let accessGroup = "[YOUR APP ID PREFIX].com.example.apple-samplecode.GenericKeychainShared"
After returning to static let accessGroup: String? = nil the problem was gone. :)
Make sure keychain sharing must on under Capabilities in project Target.
In my case the App_Name.entitlements file has different bundle id than of my project bundle id. So, I change bundle id in the App_Name.entitlements file as of my project bundle id.
e.g., Suppose your project bundle id is com.Apple.testApp then got to
App_Name.entitlements file open key Keychain Access Groups key which is of Array type.
Under item0 set value of your project bundle id as eg:- $(AppIdentifierPrefix)com.Apple.testAp.
According to #iCaramba's answer. I've found a workaround:
Stop the task to kill the app (if you are already running the app)
Launch the app on your device manually. DO NOT use Xcode
Use Xcode to re-launch the app

Adding keychain sharing to production app that already has users

We have an iOS app that has been released. The IDE is XCode6. I want to add keychain sharing to access the sessionID that exists in the app from an iOS 8 share extension.
Problem is whenever keychain sharing is turned on, the sessionID that already exists can no longer be accessed.
It can be accessed whenever keychain sharing is turned off.
This dictionary is passed into SecItemCopyMatching, which always returns -25300 (not found) whenever keychain sharing is enabled, no matter what the "Keychain Groups:" is.
[0] (null) #"svce" : #"SESSION_ID_KEY"
[1] (null) #"r_Data" : #"1"
[2] (null) #"m_Limit" : #"m_LimitOne"
[3] (null) #"class" : #"genp"
[4] (null) #"acct" : #"SESSION_ID_KEY"
[5] (null) #"pdmn" : #"ck"
Any idea why access to the key might not work? I tried setting kSecAttrAccessGroup with the bundle prefix and name and it still did not work on the simulator.
Hopefully I got your answer and the bounty :)
I had the same issue originally and came across this post, and I know you mentioned you tried with the bundle prefix and name. But let's run through a sanity check.
In the MyApp.entitlements and in MyApp Extension.entitlements I have the Keychain Access Groups set to $(AppIdentifierPrefix)com.company.MyApp (this is the default).
I accessed the value for ABCD1234 (aka AppIdentifierPrefix value) using this SO answer https://stackoverflow.com/a/20340883 however hardcoding may not be best practice here, so consider looking this a solution like this https://stackoverflow.com/a/11841898/2588957
Then note in my app all I added to make my current code to work is the following:
[keychainItem setObject:#"ABCD1234.com.company.MyApp" forKey:(__bridge id)kSecAttrAccessGroup]; before updating the item and I can now access the keychain item in my share extension.
I had a similar issue when implementing inter-app communication in iOS 7 a couple of months ago.
I found this remark on Apple's GenericKeyChain sample project:
// Apps that are built for the simulator aren't signed, so there's no keychain access group
// for the simulator to check. This means that all apps can see all keychain items when run
// on the simulator.
//
// If a SecItem contains an access group attribute, SecItemAdd and SecItemUpdate on the
// simulator will return -25243 (errSecNoAccessForItem).
So if you're testing on a Simulator you need to remove the "kSecAttrAccessGroup".
On a device it should work with this key.

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