Willow 5.0 is the latest major release of Willow, a powerful, yet lightweight logging library for iOS, macOS, tvOS and watchOS written in Swift. As a major release, following Semantic Versioning conventions, 5.0 introduces several API-breaking changes that one should be aware of.
This guide is provided in order to ease the transition of existing applications using Willow 4.x to the latest APIs.
Willow 5.0 officially supports iOS 9.0+, macOS 10.11+, tvOS 9.0+, watchOS 2.0+, Xcode 9.0+ and Swift 4.0+. If you'd like to use Willow in a project targeting Xcode 8.3 and Swift 3.1, use the latest tagged 3.x release.
Willow 5.0 contains very minor breaking changes on the log message string APIs. Most of your Willow code will be able to remain the same.
Unfortunately, in the Willow 4.0.0 release, we missed the fact that multi-line escaping closures are ambiguous with different return types. For example, the following call was ambiguous in Willow 4:
log.event {
let value = 10
return "Total value is: \(value)"
}The only way to correct the ambiguity error is to declare the closure signature for the compiler:
log.event { () -> String in
let value = 10
return "Total value is: \(value)"
}This was certainly not intended and was an unfortunate oversight on our part. Single line closures did not exhibit the issue, but multi-line escaping closures certainly do.
To resolve this issue in Willow 5, we've modified the log message string APIs to include the Message suffix.
log.eventMessage {
let value = 10
return "Total value is: \(value)"
}The LogMessage APIs do not include the Message suffix which satisfies the compiler.
Sadly we were unable to make this change in a backwards compatible way.
However, it is a very simple change to make to migrate from Willow 4 to Willow 5.
The Optional<Logger> extension APIs have also been updated to use the Message suffix for log message string APIs.
var log: Logger?
log.eventMessage {
let value = 10
return "Total value is: \(value)"
}