SwiftyTasks

Overview

Most task/operation manadgement libraries either build task infrastructure from scratch or focus on defining custom Operation subclasses.

SwiftyTask aims to build workflows on top of existing Operation infrastructure extending it with result/error handling. Any third-parrty Operation subclasses can be easily extended to support TaskProtocol and participate in complex workflows.

Tasks

SwiftyTasks defines following task-related protocols:

• AnyTask: provides list of backing tasks, is adopted by Operation class
• TaskProtocol: extenda AnyTask adding access to execution result

Library also defines following task-related classes:

• Task<ResultType>: base class, conforms to TaskProtocol, provides result handling
• BlockTask<ResultType>: subclass to wrap any code block into a Task
• AsyncTask<ResultType>: extenda Task class with asynchronous Operation state handling
• AsyncBlockTask<ResultType>: subclass to wrap any asynchronous code block into an AsyncTask
• AdapterTask<ResultType>: subclass wrapping list on operations custom result block

Operators

Following operators are defined to manage tasks:

• +=: enqueue task in OperationQueue
• <~: performs partial function application where operand on the right may be either value or task
• ~>: performs deferred function call given value/task list on the right
• ~~: adds task on the right as a dependency to task on the left

Partial Application

Task workflows circulate around partial application and functions returning Tasks.

Use <~ operator to perform partial application. Function on the left will be wrapped into a task scheduled to be executed after value on the right is ready.

Use ~> operator to convert list of values. Function on the right will be wrapped into a task scheduled to be executed when all values on the left are ready.

Finally += operator is overloaded to enqueue tasks into OperationQueue

Real-world Example

Following is an example of real-world use to create video, save it to photo library and put into a gallery folder.

let createVideoOperation = OperationQueue.main
    += CreateVideoOperation()

let createVideoAssetOperation = OperationQueue.main
    += CreateVideoAssetOperation.init(videoURL:)
    <~ createVideoOperation

let createAssetCollectionOperation = OperationQueue.main
    += CreateAssetCollectionOperation.init(title:)
    <~ "Convenience"

let addAssetToCollectionOperation = OperationQueue.main
    += AddAssetToCollectionOperation.init(asset:collection:)
    <~ createVideoAssetOperation
    <~ createAssetCollectionOperation

addAssetToCollectionOperation.completionBlock = {
    completionBlock()
}

Installation

SwiftyTasks is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod "SwiftyTasks"

Author

Victor Pavlychko, [email protected]

License

SwiftyTasks is available under the MIT license. See the LICENSE file for more info.