Update instructions for macOS sample app running DaysUntilBirthday

Samples/Swift/DaysUntilBirthday/DaysUntilBirthday.xcodeproj/project.pbxproj

@@ -652,10 +652,12 @@
 				ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++17";
 				CODE_SIGN_ENTITLEMENTS = macOS/DaysUntilBirthdayOnMac.entitlements;
+				CODE_SIGN_IDENTITY = "Apple Development";
 				CODE_SIGN_STYLE = Automatic;
 				COMBINE_HIDPI_IMAGES = YES;
 				CURRENT_PROJECT_VERSION = 1;
 				DEVELOPMENT_ASSET_PATHS = "\"macOS/Preview Content\"";
+				DEVELOPMENT_TEAM = "";
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_FILE = macOS/Info.plist;
@@ -668,6 +670,7 @@
 				MARKETING_VERSION = 1.0;
 				PRODUCT_BUNDLE_IDENTIFIER = Google.DaysUntilBirthdayOnMac;
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				PROVISIONING_PROFILE_SPECIFIER = "";
 				SDKROOT = macosx;
 				SWIFT_EMIT_LOC_STRINGS = YES;
 				SWIFT_VERSION = 5.0;
@@ -681,10 +684,11 @@
 				ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++17";
 				CODE_SIGN_ENTITLEMENTS = macOS/DaysUntilBirthdayOnMac.entitlements;
-				CODE_SIGN_STYLE = Automatic;
+				CODE_SIGN_STYLE = Manual;
 				COMBINE_HIDPI_IMAGES = YES;
 				CURRENT_PROJECT_VERSION = 1;
 				DEVELOPMENT_ASSET_PATHS = "\"macOS/Preview Content\"";
+				DEVELOPMENT_TEAM = 93P2X7NCZC;
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_FILE = macOS/Info.plist;
@@ -697,6 +701,7 @@
 				MARKETING_VERSION = 1.0;
 				PRODUCT_BUNDLE_IDENTIFIER = Google.DaysUntilBirthdayOnMac;
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				PROVISIONING_PROFILE_SPECIFIER = "Matt Mathias Macbook Wildcard";
 				SDKROOT = macosx;
 				SWIFT_EMIT_LOC_STRINGS = YES;
 				SWIFT_VERSION = 5.0;

Samples/Swift/DaysUntilBirthday/README.md

@@ -26,6 +26,25 @@ open DaysUntilBirthday.xcodeproj
 ```
 2. Run the `DaysUntilBirthday (iOS)` or `DaysUntilBirthday (macOS)` target.
 
+## A Note on running the macOS Sample
+
+If you are running the `DaysUntilBirthday` sample app on macOS, you may see an
+error like the below:
+
+```
+Error! Optional(Error Domain=com.google.GIDSignIn Code=-2 "keychain error" UserInfo={NSLocalizedDescription=keychain error})
+```
+
+This error is related to the signing of the sample app.
+You have two choices to remedy the problem.
+
+1. We suggest that you manually manage the signing of the macOS sample app so
+that you can provide a provisioning profile. Make sure to select a profile
+that is able to sign macOS apps.
+2. If you do not have the correct provisioning profile, and are unable to
+generate one, then you can add the `keychain-access-groups` entitlement to the
+`DaysUntilBirthday (macOS)` target.
+
 ## Integration Tests
 
 We run integration tests on the `DaysUntilBirthday(iOS)` sample app.