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https://github.com/BellAppLab/Backgroundable
A collection of handy classes, extensions and global functions to handle being in the background using Swift.
https://github.com/BellAppLab/Backgroundable
carthage cocoapods enqueue ios linux macos operation operationqueue osx queue swift swift-package-manager thread tvos
Last synced: about 2 months ago
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A collection of handy classes, extensions and global functions to handle being in the background using Swift.
- Host: GitHub
- URL: https://github.com/BellAppLab/Backgroundable
- Owner: BellAppLab
- License: mit
- Created: 2015-08-06T09:02:24.000Z (about 9 years ago)
- Default Branch: master
- Last Pushed: 2020-08-13T12:40:25.000Z (about 4 years ago)
- Last Synced: 2024-07-11T14:45:24.476Z (3 months ago)
- Topics: carthage, cocoapods, enqueue, ios, linux, macos, operation, operationqueue, osx, queue, swift, swift-package-manager, thread, tvos
- Language: Swift
- Homepage:
- Size: 290 KB
- Stars: 9
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Backgroundable [](#installation) [](#license)
[](#installation)
[](#swift-versions-support)
[](https://cocoapods.org/pods/Backgroundable)
[](https://github.com/Carthage/Carthage)
[](https://github.com/apple/swift-package-manager)
[](http://twitter.com/BellAppLab)
Backgroundable is a collection of handy classes, extensions and global functions to handle being in the background using Swift.
It's main focus is to add functionalities to existing `Operation`s and `OperationQueue`s, without adding overheads to the runtime (aka it's fast) nor to the developer (aka there's very little to learn).
It's powerful because it's simple.
## Specs
* iOS 10+
* tvOS 10+
* macOS 10.12+
* Swift 4.2+
* Objective-C ready
## Executing Code in the Background
Transform this:
```swift
let queue = OperationQueue()
var bgTaskId = UIBackgroundTaskInvalid
bgTaskId = UIApplication.shared.beginBackgroundTask { () -> Void in
bgTaskId = UIBackgroundTaskInvalid
}
queue.addOperation(BlockOperation(block: { () -> Void in
//do something in the background
UIApplication.shared.endBackgroundTask(bgTaskId)
}))
```
**Into this**:
```swift
inTheBackground {
//move to the background and get on with your life
}
```
## Operation Queues
Backgroundable exposes a nifty way to enqueue several operations that should be executed sequentially:
```swift
var sequentialOperations = [Operation]()
sequentialOperations.append(AsyncOperation({ (op) in
print("Executing sequential operation 1")
op.finish()
}))
sequentialOperations.append(BlockOperation({
print("Executing sequential operation 2")
//The sequential operations work with any Operation objects, not just AsyncOperations
}))
sequentialOperations.append(BlockOperation({ (op) in
print("Executing sequential operation 3")
op.finish()
}))
OperationQueue.background.addSequentialOperations(sequentialOperations, waitUntilFinished: false)
```
### Background Queue
Backgroundable also provides a global background operation queue (similar to the existing `OperationQueue.main`):
```swift
OperationQueue.background.addOperation {
//do something
}
```
This background queue is an instance of the `BackgroundQueue` class, which automatically handles background task identifiers. Whenever an operation is enqueued, a background task identifier is generated and whenever the queue is empty, the queue automatically invalidates it.
Sequential operations are guaranteed to be executed one after the other.
### Background Queue Delegate
The `BackgroundQueue` class accepts a `BackgroundQueueDelegate`, which is notified whenever the queue `backgroundQueueWillStartOperations(_:)` and when `backgroundQueueDidFinishOperations(_:)`.
This is quite handy if you want to show the network activity indicator or save a database or anything else really. The sky is the limit!
## Asyncronous Operations
An `AsyncOperation` is an easy way to perform asynchronous tasks in an `OperationQueue`. It's designed to make it easy to perform long-running tasks on an operation queue regardless of how many times its task needs to jump between threads. Only once everything is done, the `AsyncOperation` is removed from the queue.
Say we have an asynchronous function we'd like to execute in the background:
```swift
self.loadThingsFromTheInternet(callback: { (result, error) in
//process the result
})
```
If we wrapped this in an `Operation` object, we would have one small problem:
```swift
operationQueue.addOperation(BlockOperation({ [weak self] in
//We're on a background thread now; NICE!
self?.loadThingsFromTheInternet(callback: { (result, error) in
//process the result
//who knows in which thread this function returns...
})
//Aaaand... As soon as we call the load function, the operation will already be finished and removed from the queue
//But we haven't finished what we wanted to do!
//And the queue will now start executing its next operation!
//Sigh...
}))
```
The `AsyncOperation` class solves this issue by exposing the operation object itself to its execution block and only changing its `isFinished` property once everything is done:
```swift
operationQueue.addOperation(AsyncOperation({ [weak self] (op) in
//We're on a background thread now; NICE!
self?.loadThingsFromTheInternet(callback: { (result, error) in
//process the result
//then move to the main thread
onTheMainThread {
//go to the background
inTheBackground {
//do more stuff
//once everything is done, finish
op.finish()
//only now the queue will start working on the next thing
}
}
})
}))
```
Nice, huh?
### Timeouts
There's no way for an `AsyncOperation` to know when it's done (hence, we need to call `op.finish()` when its work is done). But sometimes, we developers - ahem - forget things.
Thus, in order to cover for the case where `op.finish()` may never be called (consequently blocking the `OperationQueue`), `AsyncOperation`s come with a timeout (**defaulting to 10 seconds**). After the timeout elapses, the operation is automaticallt finished and removed from the queue.
It may be the case that your `AsyncOperation`'s workload takes longer than the default timeout. If that's the case, you can define a new timeout like this:
```swift
AsyncOperation(timeout: 20, { (op) in
//perform very long task
op.finish()
})
```
Optionally, you can set the `onTimeoutCallback:` when instantiating a new `AsyncOperation` to be notified when your operations times out.
### Cancelations
As per [Apple's documentation](https://developer.apple.com/documentation/foundation/operation/1408418-iscancelled), it's always a good idea to check if your operation has been cancelled during the execution of its closure and shortcircuit it prematurely if needed. For example:
```swift
AsyncOperation({ (op) in
//do some work
guard !op.isCancelled else { return } //No need to call finish() in this case
//do some more work
})
```
### Uniqueness Policy
The uniqueness policy dictates whether `AsyncOperation`s with the same `name` should co-exist in a `BackgroundQueue`. This is great for deduplicating operations, for example:
```swift
@IBAction func refresh(_ sender: UIRefreshControl) {
let op = AsyncOperation(name: "Call to API endpoint /xyz", uniquenessPolicy: .drop) { op in
//make the call to the API
op.finish()
}
OperationQueue.background.addOperation(op)
}
```
This first time the user activates the refresh control, the operation will be added to the queue as normal, because there are no other operations with the name `"Call to API endpoint /xyz"` there yet. But if the user activates the control again before the first call to the API returns, then the `.drop` policy will make sure that a second operation is not added to the queue, since there's one operation with that name in there already. If `.replace` is set, then the previous operation is cancelled and the new one replaces it.
Neat!
## Installation
### Cocoapods
```ruby
pod 'Backgroundable', '~> 1.4'
```
Then `import Backgroundable` where needed.
### Carthage
```swift
github "BellAppLab/Backgroundable" ~> 1.4
```
Then `import Backgroundable` where needed.
### Swift Package Manager
```swift
dependencies: [
.package(url: "https://github.com/BellAppLab/Backgroundable", from: "1.4")
]
```
Then `import Backgroundable` where needed.
### Git Submodules
```shell
cd toYourProjectsFolder
git submodule add -b submodule --name Backgroundable https://github.com/BellAppLab/Backgroundable.git
```
Then drag the `Backgroundable` folder into your Xcode project.
## Author
Bell App Lab, [email protected]
### Credits
[Logo image](https://thenounproject.com/search/?q=flow&i=1469609#) by [Becris](https://thenounproject.com/Becris) from [The Noun Project](https://thenounproject.com/)
## License
Backgroundable is available under the MIT license. See the LICENSE file for more info.