Testing the Keychain - OSStatus error -34018

To answer your question: Yes, I experience the same problem. It seems to work fine when running my app. But when I run my XCTests on my device it seems that the keychain returns error -34018. The strange thing is that it doesn't happen when I run the tests on the simulator.

EDIT: I found a solution which I have explained in this answer

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

exit 1

I got this error when attempting to run keychain operations via Grand Central Dispatch. Find a way to instantiate your keychain (or keychain wrapper) on the main thread.

//results in code -34018
   static dispatch_once_t token;
    dispatch_once(&token, ^{
        keychain = [[KeychainWrapper alloc] init];


//works fine
keychain = [[KeychainWrapper alloc] init];