Repeat - modern NSTimer in GCD, debouncer and throttler
โ
โ
Star me to follow the project! โ
โ
Created by Daniele Margutti - danielemargutti.com
Repeat is small lightweight alternative to NSTimer
with a modern Swift Syntax, no strong references, multiple observers reusable instances.
Repeat is based upon GCD - Grand Central Dispatch.
It also support debouncer and throttler features.
A deep look at Timers
If you want to learn more about it check out my article on Medium: "The secret world of NSTimer".
Features Highlights
Main features offered by Repeat are:
- Simple, less verbose APIs methods to create and manage our timer. Just call
every()
oronce
to create a new Timer even in background thread. - Avoid strong references to the destination target and avoid NSObject inheritance.
- Support multiple observers to receive fire events from timer.
- Ability to pauseย , startย , resume and reset our timer without allocating a new instance.
- Ability to set different repeat modes (
infinite
ย : infinite sequence of fires, at regular intervals,finite
ย : a finite sequence of fires, at regular intervals,once
ย : a single fire events at specified interval since start).
Moreover Repeat also provide supports for:
- Debouncer: Debouncer will delay a function call, and every time it's getting called it will delay the preceding call until the delay time is over.
- Throttler: Throttling wraps a block of code with throttling logic, guaranteeing that an action will never be called more than once each specified interval.
Other Libraries You May Like
I'm also working on several other projects you may like. Take a look below:
Library | Description |
---|---|
SwiftDate | The best way to manage date/timezones in Swift |
Hydra | Write better async code: async/await & promises |
Flow | A new declarative approach to table managment. Forget datasource & delegates. |
SwiftRichString | Elegant & Painless NSAttributedString in Swift |
SwiftLocation | Efficient location manager |
SwiftMsgPack | Fast/efficient msgPack encoder/decoder |
Documentation
Timer
Note: As any other object Repeater
class is subject to the standard memory management rules. So once you create your timer instance you need to retain it somewhere in order to avoid premature deallocation just after the start command.
Create single fire timer
The following code create a timer which fires a single time after 5 seconds.
self.timer = Repeater.once(after: .seconds(5)) { timer in
// do something
}
Create recurrent finite timer
The following code create a recurrent timer: it will fire every 10 minutes for 5 times, then stops.
self.timer = Repeater.every(.minutes(10), count: 5) { timer in
// do something
}
Create recurrent infinite timer
The following code create a recurrent timer which fires every hour until it is manually stopped .
self.timer = Repeater.every(.hours(1)) { timer in
// do something
}
Manage a timer
You can create a new instance of timer and start as needed by calling the start()
function.
self.timer = Repeater(interval: .seconds(5), mode: .infinite) { _ in
// do something
}
timer.start()
Other functions are:
start()
: start a paused or newly created timerpause()
: pause a running timerreset(_ interval: Interval, restart: Bool)
: reset a running timer, change the interval and restart again if set.fire()
: manually fire an event of the timer from an external source
Properties:
.id
: unique identifier of the timer.mode
: define the type of timer (infinite
,finite
,once
).remainingIterations
: for a.finite
mode it contains the remaining number of iterations before it finishes.
Adding/Removing Observers
By default a new timer has a single observer specified by the init functions. You can, however, create additional observer by using observe()
function. The result of this call is a token identifier you can use to remove the observer in a second time.
Timer instance received in callback is weak.
let token = timer.observe { _ in
// a new observer is called
}
timer.start()
You can remove an observer by using the token:
timer.remove(token)
Observing state change
Each timer can be in one of the following states, you can observe via .state
property:
.paused
: timer is in idle (never started yet) or paused.running
: timer is currently active and running.executing
: registered observers are being executed.finished
: timer lifecycle is finished (it's valid for a finite/once state timer)
You can listen for state change by assigning a function callback for .onStateChanged
property.
timer.onStateChanged = { (timer,newState) in
// your own code
}
Debouncer
Since 0.5 Repeater introduced Debouncer
class.
The Debouncer will delay a function call, and every time it's getting called it will delay the preceding call until the delay time is over.
The debounce function is an extremely useful tool that can help throttle requests. It is different to throttle though as throttle will allow only one request per time period, debounce will not fire immediately and wait the specified time period before firing the request. If there is another request made before the end of the time period then we restart the count. This can be extremely useful for calling functions that often get called and are only needed to run once after all the changes have been made.
let debouncer = Debouncer(.seconds(10))
debouncer.callback = {
// your code here
}
// Call debouncer to start the callback after the delayed time.
// Multiple calls will ignore the older calls and overwrite the firing time.
debouncer.call()
(Make sure to check out the Unit Tests for further code samples.)
Throttler
Since 0.5 Repeater introduced Throttler
class.
Throttling wraps a block of code with throttling logic, guaranteeing that an action will never be called more than once each specified interval. Only the last dispatched code-block will be executed when delay has passed.
let throttler = Throttler(time: .milliseconds(500), {
// your code here
})
// Call throttler. Defined block will never be called more than once each specified interval.
throttler.call()
Requirements
Repeat is compatible with Swift 4.x. All Apple platforms are supported:
- iOS 8.0+
- macOS 10.10+
- watchOS 2.0+
- tvOS 9.0+
Latest Version
Latest version of Repeat is 0.5.4 published on 2018/04/28. Full changelog is available in CHANGELOG.md file.
Installation
Install via CocoaPods
CocoaPods is a dependency manager for Objective-C, which automates and simplifies the process of using 3rd-party libraries like Repeat in your projects. You can install it with the following command:
$ sudo gem install cocoapods
CocoaPods 1.0.1+ is required to build Repeat.
Install via Podfile
To integrate Repeat into your Xcode project using CocoaPods, specify it in your Podfile
:
source 'https://github.com/CocoaPods/Specs.git'
platform :ios, '8.0'
target 'TargetName' do
use_frameworks!
pod 'Repeat'
end
Then, run the following command:
$ pod install
Carthage
Carthage is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks.
You can install Carthage with Homebrew using the following command:
$ brew update
$ brew install carthage
To integrate Repeat into your Xcode project using Carthage, specify it in your Cartfile
:
github "malcommac/Repeat"
Run carthage
to build the framework and drag the built Repeat.framework
into your Xcode project.