Lightweight Observable 2.0 Migration Guide.md

Lightweight Observable 2.0 Migration Guide

Lightweight Observable 2.0 is the latest major release of Lightweight Observable. As a major release, following Semantic Versioning conventions, 2.0 introduces some API-breaking changes that one should be aware of.

This guide is provided in order to ease the transition of existing applications using Lightweight Observable 1.x to the latest APIs, as well as explain the design and structure of new and changed functionality.

Benefits of Upgrading

• PublishSubject: A new subject type, that starts empty and only emits new elements to subscribers.

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Breaking API Changes

Type of property value changed to optional

As a PublishSubject doesn't have an initial value, the property value of the class Observable has changed to an optional type. However, it's always better to subscribe to a given observable! This shortcut should only be used during testing.

Removed property asObservable from class Variable

Eventhough it is a bit more readable there is no need to write .asObservable to cast a Variable to an Observable as Swift can do the casting automatically.

Instead of writing:

var someVariable: Observable<Int> = {
    someVariableSubject.asObservable
}

you can simply write:

var someVariable: Observable<Int> = {
    someVariableSubject
}

lazy var someVariable: Observable<Int> = someVariableSubject

Therefore this computed property has been removed.