RemoteConfig invalid array decoding

[Harryjeffs]

[REQUIRED] Step 1: Describe your environment

• Xcode version: 13.4.1
• Firebase SDK version: 9.2.0
• Installation method: Swift Package Manage
• Firebase Component: Remote Config
• Target platform(s): iOS

[REQUIRED] Step 2: Describe the problem

Steps to reproduce:

Example XML:
RemoteConfigDefaults.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
	<dict>
		<key>state</key>
		<string>["yes", "no", "maybe"]</string>
	</dict>
</plist>

Fetching the data is fine however decoding runs into the following error:

DecodingError
▿ typeMismatch : 2 elements
- .0 : Swift.Array
▿ .1 : Context
- codingPath : 0 elements
- debugDescription : "Expected to decode Array but found FirebaseRemoteConfigValueDecoderHelper instead."
- underlyingError : nil

Relevant Code:

remoteConfig = RemoteConfig.remoteConfig()
let settings = RemoteConfigSettings()
remoteConfig.configSettings = settings
remoteConfig.setDefaults(fromPlist: "RemoteConfigDefaults")
do {
	config = try remoteConfig.decoded(asType: [String].self)
} catch {
	print(error)
}

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[paulb777]

@Harryjeffs Thanks for the report. It's possible that this is addressed by the recently merged #8307. We'll need to investigate.

[Harryjeffs]

Thanks for tagging this @paulb777 . I have updated my project to 9.3.0 to include the changes from #8307 however the issue still occurs with the most basic setup (string array). Furthermore, the issue occurs with both the device defaults & the remote response. Unless my setup is grossly wrong but passes the firebase console JSON check.

[paulb777]

@Harryjeffs Thanks for the update. We'll take a deeper look next week.

[jakekrog]

@Harryjeffs what's probably going on is you're using a JSON string instead of a plist array... this should work in 9.3.0:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
	<dict>
		<key>state</key>
		<array>
			<string>yes</string>
			<string>no</string>
			<string>maybe</string>
		</array>
	</dict>
</plist>

see also: https://github.com/firebase/firebase-ios-sdk/blob/aaeb5f43fcfeaa49340fa1be7a74ed7bfa5152bf/FirebaseRemoteConfig/Tests/Unit/Defaults-testInfo.plist

[paulb777]

@jakekrog Good catch and thanks for the explanation!

@Harryjeffs Let us know if that resolves your question.

[Harryjeffs]

Thanks for that @jakekrog. Unfortunately the issue lies with JSON strings (generated via firebase console)

Here is a more realistic scenario that I've encountered. The onboarding & isAppActive keys will fail to encode with the same error as above. The paywall key correctly encodes, along with the child array (features).

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>isAppActive</key>
	<string>["yes", "no", "maybe"]</string>
	<key>onboarding</key>
	<string>[{"title":"Lorem ipsum","imageName":"pencil","description":"Lorem ipsum dolor sit amet, consectetur adipiscing elit","advanceButtonTitle":"Next"},{"title":"Lorem ipsum","imageName":"pencil","description":"Lorem ipsum dolor sit amet, consectetur adipiscing elit","advanceButtonTitle":null},{"title":"Lorem ipsum","imageName":"pencil","description":"Lorem ipsum dolor sit amet, consectetur adipiscing elit","advanceButtonTitle":null}]</string>
	<key>paywall</key>
	<string>{"title":"Upgrade Today!","subtitle":"Start your %d day free trial today","ctaText":"Unlock Now","features":[{"systemImage":"camera","description":"Lorum Ipsum"},{"systemImage":"lock.open.fill","description":"Lorum Ipsum"},{"systemImage":"xmark","description":"Lorum Ipsum"}],"legal":{"title":"More information visit our /n Terms and Conditions","linkSubString":"Terms and Conditions","subStringLink":"https://apple.com"}}</string>
</dict>
</plist>

One workaround I tried was converting onboarding to an object, though this yielded the same error.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>isAppActive</key>
	<string>["yes", "no", "maybe"]</string>
	<key>onboarding</key>
	<string>{ "titles": [{"title":"Lorem ipsum","imageName":"pencil","description":"Lorem ipsum dolor sit amet, consectetur adipiscing elit","advanceButtonTitle":"Next"},{"title":"Lorem ipsum","imageName":"pencil","description":"Lorem ipsum dolor sit amet, consectetur adipiscing elit","advanceButtonTitle":null},{"title":"Lorem ipsum","imageName":"pencil","description":"Lorem ipsum dolor sit amet, consectetur adipiscing elit","advanceButtonTitle":null}]}</string>
	<key>paywall</key>
	<string>{"title":"Upgrade Today!","subtitle":"Start your %d day free trial today","ctaText":"Unlock Now","features":[{"systemImage":"camera","description":"Lorum Ipsum"},{"systemImage":"lock.open.fill","description":"Lorum Ipsum"},{"systemImage":"xmark","description":"Lorum Ipsum"}],"legal":{"title":"More information visit our /n Terms and Conditions","linkSubString":"Terms and Conditions","subStringLink":"https://apple.com"}}</string>
</dict>
</plist>

The code is the same as the original issue but hopefully, this helps with debugging.

[paulb777]

Thanks for your patience @Harryjeffs.

I've reproduced the issue and confirmed that the Codable implementation does not support array and dictionary defaults set by a plist. I'm working on a fix and hope to have a PR up later this week.

In the meantime, you can use the non-Codable APIs as a workaround.

Thanks for your persistence in helping us understand the issue.