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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
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.
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.
I recently installed iOS 7.1 simulator and the new Xcode 5.1. My App worked in iOS 7 fine. I'm using the KeychainItemWrapper class from Apple.
After the update it crashed with the following message:
*** Assertion failure in -[KeychainItemWrapper writeToKeychain]
Specifically at line 299:
NSAssert( result == noErr, #"Couldn't update the Keychain Item." );
Error is hear -25300 (errSecItemNotFound)
I have specified the Keychain Access Group in my entitlements file. This error occurred only in the iOS 7.1 Simulator and not on a real iPhone or the 7.0 Simulator.
Does anyone know what changed with Keychain in 7.1 ?
Well KeychainItemWrapper is a old implementation full of bugs. I would recommend using another wrapper, or write your own.
That being said, I used to have many error but not this one. Basically what happens is while saving it checks that your item is already in the keychain, in order to add it or just update it. Here that check returns true even though the item is quite different, so it cannot update because SecItemUpdate believes it does not exist.
What you should do is reset your keychain, you have two options for this :
On the simulator Menu Simulator->Reset content and settings
Run this snippet somewhere in your code :
Based on Vegard answer here Reset An iPhone App's Keychain
-(void)resetKeychain {
[self deleteAllKeysForSecClass:kSecClassGenericPassword];
[self deleteAllKeysForSecClass:kSecClassInternetPassword];
[self deleteAllKeysForSecClass:kSecClassCertificate];
[self deleteAllKeysForSecClass:kSecClassKey];
[self deleteAllKeysForSecClass:kSecClassIdentity];
}
-(void)deleteAllKeysForSecClass:(CFTypeRef)secClass {
NSMutableDictionary* dict = [NSMutableDictionary dictionary];
[dict setObject:(__bridge id)secClass forKey:(__bridge id)kSecClass];
OSStatus result = SecItemDelete((__bridge CFDictionaryRef) dict);
NSAssert(result == noErr || result == errSecItemNotFound, #"Error deleting keychain data (%ld)", result);
}
Keychain continues to work under iOS 7.1. Your issue is related to Simulator itself. Simulator does not allow to store certain keys as far as I know, and this is consistent between iOS 7.0 and iOS 7.1.
If you run your app on a real device, the crash will disappear.
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