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  • v2.0.0-alpha.1 Changes

    πŸš€ This is the first alpha release of ReactiveSwift 2.0. It requires Swift 3.1 (Xcode 8.3).

    πŸ”„ Changes

    🚦 Modified Signal lifetime semantics (#355)

    🚦 The Signal lifetime semantics is modified to improve interoperability with memory debugging tools. ReactiveSwift 2.0 adopted a new Signal internal which does not exploit deliberate retain cycles that consequentially confuse memory debugging tools.

    🚦 A Signal is now automatically and silently disposed of, when:

    🚦 1. the Signal is not retained and has no active observer; or

    1. (New) both the Signal and its input observer are not retained.

    It is expected that memory debugging tools would no longer report irrelevant negative leaks that were once caused by the ReactiveSwift internals.

    🚦 SignalProducer resource management (#334)

    🚦 SignalProducer now uses Lifetime for resource management. You may observe the Lifetime for the disposal of the produced Signal.

    let producer = SignalProducer<Int, NoError> { observer, lifetime in
        if let disposable = numbers.observe(observer) {

    πŸš€ Two Disposable-accepting methods Lifetime.Type.+= and Lifetime.add are provided to aid migration, and are subject to removal in a future release.

    🚦 Signal and SignalProducer

    🚦 1. All Signal and SignalProducer operators now belongs to the respective concrete types. (#304)

    Custom operators should extend the concrete types directly. SignalProtocol and SignalProducerProtocol should be used only for constraining associated types.

    βœ… 1. combineLatest and zip are optimised to have a constant overhead regardless of arity, mitigating the possibility of stack overflow. (#345)

    1. flatMap(_:transform:) is renamed to flatMap(_:_:). (#339)

    2. promoteErrors(_:)is renamed to promoteError(_:). (#408)

    🚦 1. Event is renamed to Signal.Event. (#376)

    🚦 1. Observer is renamed to Signal.Observer. (#376)


    1. Action(input:_:), Action(_:), Action(enabledIf:_:) and Action(state:enabledIf:_:) are renamed to Action(state:execute:), Action(execute:), Action(enabledIf:execute:) and Action(state:enabledIf:execute:) respectively. (#325)


    1. The memory overhead of property composition has been considerably reduced. (#340)


    1. The BindingSource now requires only a producer representation of self. (#359)

    2. The <~ operator overloads are now provided by BindingTargetProvider. (#359)


    1. SimpleDisposable and ActionDisposable has been folded into AnyDisposable. (#412)

    2. CompositeDisposable.DisposableHandle is replaced by Disposable?. (#363)

    3. The += operator overloads for CompositeDisposable are now hosted inside the concrete types. (#412)


    🐎 1. Improved the performance of Bag. (#354)

    1. RemovalToken is renamed to Bag.Token. (#354)

    ⏱ Schedulers

    ⏱ 1. Scheduler gains a class bound. (#333)


    1. Lifetime.ended now uses the inhabitable Never as its value type. (#392)


    1. Signal and Atomic now use os_unfair_lock when it is available. (#342)

    βž• Additions

    1. FlattenStrategy.race is introduced. (#233, kudos to @inamiy)

    race flattens whichever inner signal that first sends an event, and ignores the rest.

    1. FlattenStrategy.concurrent is introduced. (#298, kudos to @andersio)

    concurrent starts and flattens inner signals according to the specified concurrency limit. If an inner signal is received after the limit is reached, it would be queued and drained later as the in-flight inner signals terminate.

    1. New operators: reduce(into:) and scan(into:). (#365, kudos to @ikesyo)

    These variants pass to the closure an inout reference to the accumulator, which helps the performance when a large value type is used, e.g. collection.

    🚦 1. Property(initial:then:) gains overloads that accept a producer or signal of the wrapped value type when the value type is an Optional. (#396)

    πŸ—„ Deprecations and Removals

    🚚 1. The requirement BindingSource.observe(_:during:) and the implementations have been removed.

    🚚 1. All Swift 2 (ReactiveCocoa 4) obsolete symbols have been removed.

    πŸ—„ 1. All deprecated methods and protocols in ReactiveSwift 1.1.x are no longer available.


    Thank you to all of @ReactiveCocoa/reactiveswift and all our contributors, but especially to @andersio, @calebd, @eimantas, @ikesyo, @inamiy, @Marcocanc, @mdiep, @NachoSoto, @sharplet and @tjnet. ReactiveSwift is only possible due to the many hours of work that these individuals have volunteered. ❀️

  • v1.1.3 Changes

    πŸ—„ Deprecation

    🚚 1. observe(_:during:) is now deprecated. It would be removed in ReactiveSwift 2.0. Use take(during:) and the relevant observation API of Signal, SignalProducer and Property instead. (#374)

  • v1.1.2 Changes

    πŸ”„ Changes

    πŸ›  1. Fixed a rare occurrence of interrupted events being emitted by a Property. (#362)

  • v1.1.1 Changes

    πŸ”„ Changes

    🚦 1. The properties Signal.negated, SignalProducer.negated and Property.negated are deprecated. Use its operator form negate() instead.

  • v1.1 Changes

    βž• Additions


    🚦 1. New boolean operators: and, or and negated; available on Signal<Bool, E>, SignalProducer<Bool, E> and Property<Bool, E> types. (#160, kudos to @cristianames92)

    1. New operator filterMap. (#232, kudos to @RuiAAPeres) ⏱ 3. New operator lazyMap(on:_:). It coalesces value events when they are emitted at a rate faster than the rate the given scheduler can handle. The transform is applied on only the coalesced and the uncontended values. (#240, kudos to @liscio)
    2. New protocol BindingTargetProvider, which replaces BindingTargetProtocol. (#254, kudos to @andersio)

    🚦 SignalProducer

    🚦 5. New initializer SignalProducer(_:), which takes a @escaping () -> Value closure. It is similar to SignalProducer(value:), but it lazily evaluates the value every time the producer is started. (#240, kudos to @liscio)


    1. New method Lifetime.observeEnded(self:). This is now the recommended way to explicitly observe the end of a Lifetime. Use Lifetime.ended only if composition is needed. (#229, kudos to @andersio)
    2. New factory method Lifetime.make(), which returns a tuple of Lifetime and Lifetime.Token. (#236, kudos to @sharplet)


    1. ValidatingProperty: A mutable property that validates mutations before committing them. (#182, kudos to @andersio). πŸ’» 9. A new interactive UI playground: ReactiveSwift-UIExamples.playground. It demonstrates how ValidatingProperty can be used in an interactive form UI. (#182)

    πŸ”„ Changes

    🚦 1. Flattening a signal of Sequence no longer requires an explicit FlattenStrategy. (#199, kudos to @dmcrodrigues)

    1. BindingSourceProtocol has been renamed to BindingSource. (#254) ⏱ 3. SchedulerProtocol and DateSchedulerProtocol has been renamed to Scheduler and DateScheduler, respectively. (#257)
    2. take(during:) now handles ended Lifetime properly. (#229)

    πŸ—„ Deprecations

    πŸ—„ 1. AtomicProtocol has been deprecated. (#279) πŸ—„ 2. ActionProtocol has been deprecated. (#284) πŸ—„ 3. ObserverProtocol has been deprecated. (#262) πŸ—„ 4. BindingTargetProtocol has been deprecated. (#254)

  • v1.0.1 Changes

    πŸ”„ Changes

    πŸ›  1. Fixed a couple of infinite feedback loops in Action. (#221) πŸš€ 2. Fixed a race condition of Signal which might result in a deadlock when a signal is sent a terminal event as a result of an observer of it being released. (#267)

    Kudos to @mdiep, @sharplet and @andersio who helped review the pull requests.

  • v1.0 Changes

    πŸš€ This is the first major release of ReactiveSwift, a multi-platform, pure-Swift functional reactive programming library spun off from ReactiveCocoa. As Swift continues to expand beyond Apple’s platforms, we hope that ReactiveSwift will see broader adoption. To learn more, please refer to ReactiveCocoa’s CHANGELOG.

    Major changes since ReactiveCocoa 4 include:

    • ⚑️ Updated for Swift 3

    APIs have been updated and renamed to adhere to the Swift 3 API Design Guidelines.

    • 🚦 Signal Lifetime Semantics

    Signals now live and continue to emit events only while either (a) they have observers or (b) they are retained. This clears up a number of unexpected cases and makes Signals much less dangerous.

    • Reactive Proxies

    Types can now declare conformance to ReactiveExtensionsProvider to expose a reactive property that’s generic over self. This property hosts reactive extensions to the type, such as the ones provided on NotificationCenter and URLSession.

    • Property Composition

    Propertys can now be composed. They expose many of the familiar operators from Signal and SignalProducer, including map, flatMap, combineLatest, etc.

    • Binding Primitives

    BindingTargetProtocol and BindingSourceProtocol have been introduced to allow binding of observable instances to targets. BindingTarget is a new concrete type that can be used to wrap a settable but non-observable property.

    • Lifetime

    Lifetime is introduced to represent the lifetime of any arbitrary reference type. This can be used with the new take(during:) operator, but also forms part of the new binding APIs.

    • πŸ†“ Race-free Action

    A new Action initializer Action(state:enabledIf:_:) has been introduced. It allows the latest value of any arbitrary property to be supplied to the execution closure in addition to the input from apply(_:), while having the availability being derived from the property.

    This eliminates a data race in ReactiveCocoa 4.x, when both the enabledIf predicate and the execution closure depend on an overlapping set of properties.

    Extensive use of Swift’s @available declaration has been used to ease migration from ReactiveCocoa 4. Xcode should have fix-its for almost all changes from older APIs.

    Thank you to all of @ReactiveCocoa/ReactiveSwift and all our contributors, but especially to @andersio, @liscio, @mdiep, @nachosoto, and @sharplet. ReactiveSwift is only possible due to the many hours of work that these individuals have volunteered. ❀️