Prepare 5.0.0 release

[gwhelanLD]

[5.0.0] - 2020-07-23

This major version has an accompanying Migration Guide. Please see the guide for more information on updating to this version of the SDK, as the following is just a summary of the changes.

Added

• Support for multiple LaunchDarkly projects or environments. Each set of feature flags associated with a mobile key is called an environment. This adds:
  • LDConfig.setSecondaryMobileKeys and LDConfig.getSecondaryMobileKeys which allows configuring a mapping of names to the SDK keys for each additional environment. LDConfig.mobileKey is still required, and represents the primary environment.
  • LDClient.get(environment: ) which allows retrieving an LDClient instance for a given environment after the SDK has been initialized.
  • Equivalent methods have been added to the Objective-C bindings for LDConfig and LDClient.
• The SDK now periodically sends diagnostic data to LaunchDarkly, describing the version and configuration of the SDK, the operating system the SDK is running on, the device type (such as "iPad"), and performance statistics. No credentials, device IDs, or other identifiable values are included. This behavior can be disabled or configured with the new LDConfig properties diagnosticOptOut and diagnosticRecordingInterval.
• The SDK can now be configured with LDConfig.wrapperName and LDConfig.wrapperVersion to send an additional header (X-LaunchDarkly-Wrapper) in requests to LaunchDarkly. This was added so that the usage of wrapper libraries (such as the React Native SDK) could be recorded independently.
• Added the evaluationReasons field to the Objective-C bindings for LDConfig to allow configuring the SDK to request evaluation reasons when the application is written in Objective-C.
• The SDK now supports using the Swift Package Manager to include the SDK as a dependency.
• LDInvalidArgumentError that is thrown on incorrect API usage.
• Added typeMismatch field to ObjcLD<T>ChangedFlag classes (bound to LD<T>ChangedFlag in Objective-C) that is true/YES when the flag value did not match the registered observer.

Changed (build)

• Minimum deployment targets have been changed as follows:
  • iOS 8.0 -> 10.0
  • macOS 10.10 -> 10.12
  • tvOS 9.0 -> 10.0
  • watchOS 2.0 -> 3.0
• The SDK has replaced the internal dependency on the Objective-C eventsource implementation DarklyEventSource with a pure Swift implementation LDSwiftEventSource. Build configurations that manually specify the DarklyEventSource dependency framework may require additional upgrade steps. See the Migration Guide for more information.
• Internally, the SDK no longer includes its dependencies using CocoaPods and Carthage. This simplifies including the SDK as a subproject of your application for integrating the SDK without a package manager.

Changed (API)

• The LDClient instance method start has been replaced with a static method LDClient.start for initializing all configured environments.
• LDChangedFlag no longer includes the oldValueSource and newValueSource properties, as LDFlagValueSource was removed.
• The following were renamed for consistency internally and with other SDKs:
  • LDClient.reportEvents() has been renamed to LDClient.flush().
  • LDClient.stop() has been renamed to LDClient.close().
  • LDClient.trackEvent(key: data: ) method have been renamed to LDClient.track(key: data: )
  • LDClient.allFlagValues has been renamed to LDClient.allFlags.
  • EvaluationDetail has been renamed to LDEvaluationDetail.
  • The ObjC<T>EvaluationDetail classes have been renamed to corresponding ObjcLD<T>EvaluationDetail. The names when exposed in Objective-C have been updated to replace the ObjC prefix with LD, e.g. ObjCStringEvaluationDetail to LDStringEvaluationDetail.
• LDClient.track no longer throws JSONError and instead throws LDInvalidArgumentError.
• The fallback parameter of all LDClient and ObjcLDClient variation methods has been renamed to defaultValue to help distinguish it from fallback values in rules specified in the LaunchDarkly dashboard.

Changed (behavioral)

• The maximum backoff delay between failed streaming connections has been reduced from an hour to 30 seconds. This is to prevent being unable to receive new flag values for up to an hour if the SDK has reached its maximum backoff due to a period of network connectivity loss.
• The backoff on streaming connections will not be reset after just a successful connection, rather waiting for a healthy connection for one minute after receiving flags. This is to reduce congestion in poor network conditions or if extreme load prevents the LaunchDarkly service from maintaining an active streaming connection.
• When sending events to LaunchDarkly, the SDK will now retry the request after a one second delay if it fails.
• When events fail to be sent to LaunchDarkly, the SDK will no longer retain the events. This prevents double recording events when the LaunchDarkly service received the event but the SDK failed to receive the acknowledgement.
• The LDClient.identify, LDClient.flush, LDClient.setOnline, and LDClient.close instance methods now operate on all configured environments. Any completion arguments will complete when the operation has completed for all configured environments.

Removed

• The LDClient.shared static property and its ObjcLDClient.sharedInstance wrapper property has been removed. After calling LDClient.start, the initialized instances can be retrieved with LDClient.get(environment: ).
• The LDClient.config and its ObjcLDClient.config wrapper property has been removed, configuration of the SDK should be done with LDClient.start.
• The LDClient.user and its ObjcLDClient.user wrapper property has been removed. The initial user should be configured with LDClient.start, and updates to the user should be performed with LDClient.identify.
• LDFlagValueSource and ObjcLDFlagValueSource were removed in favor of using LDEvaluationDetail and ObjcLD<T>EvaluationDetail.
• The Objective-C wrapper classes ObjcLD<T>VariationValue (bound in Objective-C to LD<T>VariationValue), which wrapped a flag value and its source, have been removed.
• variationAndSource methods were removed from LDClient and its ObjcLDClient wrapper in favor of variationDetail methods.
• LDUser.init?(object: ) and corresponding ObjcLDUser failable initializers were removed.
• JSONError and JSONErrorDomain extensions on JSONSerialization were removed.
• Removed isEqual extension to Array, this was only intended for internal SDK use.
• Removed == and != extension to Optional<[String: Any]> (note that this was not declared as Equatable conformance). This extension was only intended for internal SDK use.
• Removed LDFlagValue enum and the ObjcLDFlagValue wrapper which were exposed but not used in any public APIs.
• Removed Sysctl struct (only available on macOS) which was only intended for internal SDK use.