Code Quality Rank: L5
Programming language: Swift
License: MIT License
Tags: Events    
Latest version: v7.0.0

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Promises simplify asynchronous programming, freeing you up to focus on the more important things. They are easy to learn, easy to master and result in clearer, more readable code. Your co-workers will thank you.

UIApplication.shared.isNetworkActivityIndicatorVisible = true

let fetchImage = URLSession.shared.dataTask(.promise, with: url).compactMap{ UIImage(data: $0.data) }
let fetchLocation = CLLocationManager.requestLocation().lastValue

firstly {
    when(fulfilled: fetchImage, fetchLocation)
}.done { image, location in
    self.imageView.image = image
    self.label.text = "\(location)"
}.ensure {
    UIApplication.shared.isNetworkActivityIndicatorVisible = false
}.catch { error in
    self.show(UIAlertController(for: error), sender: self)

PromiseKit is a thoughtful and complete implementation of promises for any platform that has a swiftc. It has delightful specializations for iOS, macOS, tvOS and watchOS. It is a top-100 pod used in many of the most popular apps in the world.



Xcode >= 12.0 or Swift >= 5.3.

For earlier Swifts, Xcodes or for Objective-C support, use PromiseKit 6.

Quick Start

In your Package.swift:

    .package(url: "https://github.com/mxcl/PromiseKit", from: "7.0.0-rc1")

For more detailed installation instructions or for other package managers see our [Installation Guide].

Professionally Supported PromiseKit is Now Available

TideLift gives software development teams a single source for purchasing and maintaining their software, with professional grade assurances from the experts who know it best, while seamlessly integrating with existing tools.

Get Professional Support for PromiseKit with TideLift.

Other Sponsorship

Maintaining this project is work, if your company uses this project please sponsor it either via Tidelift or GitHub Sponsors.


  • Handbook
    • [Getting Started](Documents/GettingStarted.md)
    • [Promises: Common Patterns](Documents/CommonPatterns.md)
    • [Cancelling Promises](Documents/Cancel.md)
    • [Frequently Asked Questions](Documents/FAQ.md)
  • Manual
    • [Installation Guide](Documents/Installation.md)
    • [Troubleshooting](Documents/Troubleshooting.md) (e.g., solutions to common compile errors)
    • [Appendix](Documents/Appendix.md)
  • API Reference


Promises are only as useful as the asynchronous tasks they represent. Thus, we have converted (almost) all of Apple’s APIs to promises. You can use the extensions by adding the appropriate library to your Package.swift and then importing it (eg. import PMKFoundation).

See our [Installation Guide](Documents/Installation.md) for usage details.

Browse the Sources folder here for a list of available extensions.


Please check our [Troubleshooting Guide](Documents/Troubleshooting.md), and if after that you still have a question, ask at our Gitter chat channel or on our bug tracker.

Security & Vulnerability Reporting or Disclosure


*Note that all licence references and agreements mentioned in the PromiseKit README section above are relevant to that project's source code only.