ios 在 Swift 中每 x 分钟做一些事情
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/25951980/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Do something every x minutes in Swift
提问by JOSEFtw
How can I run a function every minute?
In JavaScript I can do something like setInterval, does something similar exist in Swift?
如何每分钟运行一个函数？在 JavaScript 中，我可以做类似的setInterval事情，Swift 中是否存在类似的东西？
Wanted output:
想要的输出：
Hello World once a minute...
你好世界每分钟一次...
回答by Unheilig
var helloWorldTimer = NSTimer.scheduledTimerWithTimeInterval(60.0, target: self, selector: Selector("sayHello"), userInfo: nil, repeats: true)
func sayHello()
{
NSLog("hello World")
}
Remember to import Foundation.
记得导入Foundation。
Swift 4:
斯威夫特 4：
var helloWorldTimer = Timer.scheduledTimer(timeInterval: 60.0, target: self, selector: #selector(ViewController.sayHello), userInfo: nil, repeats: true)
@objc func sayHello()
{
NSLog("hello World")
}
回答by Rob
If targeting iOS version 10 and greater, you can use the block-based rendition of Timer, which simplifies the potential strong reference cycles, e.g.:
如果针对 iOS 10 及更高版本，您可以使用 的基于块的再现Timer，这简化了潜在的强引用循环，例如：
weak var timer: Timer?
func startTimer() {
timer?.invalidate() // just in case you had existing `Timer`, `invalidate` it before we lose our reference to it
timer = Timer.scheduledTimer(withTimeInterval: 60.0, repeats: true) { [weak self] _ in
// do something here
}
}
func stopTimer() {
timer?.invalidate()
}
// if appropriate, make sure to stop your timer in `deinit`
deinit {
stopTimer()
}
While Timeris generally best, for the sake of completeness, I should note that you can also use dispatch timer, which is useful for scheduling timers on background threads. With dispatch timers, since they're block-based, it avoids some of the strong reference cycle challenges with the old target/selectorpattern of Timer, as long as you use weakreferences.
虽然Timer通常是最好的，但为了完整起见，我应该注意您也可以使用调度计时器，这对于在后台线程上调度计时器很有用。使用调度计时器，因为它们是基于块的，所以只要您使用引用，它就可以避免旧的target/selector模式的一些强引用循环挑战。Timerweak
So:
所以：
var timer: DispatchSourceTimer?
func startTimer() {
let queue = DispatchQueue(label: "com.domain.app.timer") // you can also use `DispatchQueue.main`, if you want
timer = DispatchSource.makeTimerSource(queue: queue)
timer!.schedule(deadline: .now(), repeating: .seconds(60))
timer!.setEventHandler { [weak self] in
// do whatever you want here
}
timer!.resume()
}
func stopTimer() {
timer?.cancel()
timer = nil
}
deinit {
self.stopTimer()
}
For more information, see the the Creating a Timersection of Dispatch Source Examplesin the Dispatch Sourcessection of the Concurrency Programming Guide.
有关更多信息，请参阅并发编程指南的调度源部分中的调度源示例的创建计时器部分。
For Swift 2, see previous revision of this answer.
对于 Swift 2，请参阅此答案的先前修订版。
回答by John T
Here's an update to the NSTimeranswer, for Swift 3 (in which NSTimerwas renamed to Timer) using a closure rather than a named function:
这是NSTimer答案的更新，对于使用闭包而不是命名函数的Swift 3（其中NSTimer已重命名为Timer）：
var timer = Timer.scheduledTimer(withTimeInterval: 60, repeats: true) {
(_) in
print("Hello world")
}
回答by algrid
If you can allow for some time drifthere's a simple solution executing some code every minute:
如果您可以允许一些时间漂移，这里有一个简单的解决方案，每分钟执行一些代码：
private func executeRepeatedly() {
// put your code here
DispatchQueue.main.asyncAfter(deadline: .now() + 60.0) { [weak self] in
self?.executeRepeatedly()
}
}
Just run executeRepeatedly()once and it'll be executed every minute. The execution stops when the owning object (self) is released. You also can use a flag to indicate that the execution must stop.
只需运行executeRepeatedly()一次，它将每分钟执行一次。当拥有对象 ( self) 被释放时，执行停止。您还可以使用标志来指示必须停止执行。
回答by Bas
You can use Timer(swift 3)
您可以使用Timer(swift 3)
var timer = Timer.scheduledTimerWithTimeInterval(60, target: self, selector: Selector("function"), userInfo: nil, repeats: true)
In selector() you put in your function name
在 selector() 中输入函数名称
回答by Can
In swift 3.0 the GCD got refactored:
在 swift 3.0 中，GCD 被重构了：
let timer : DispatchSourceTimer = DispatchSource.makeTimerSource(flags: [], queue: DispatchQueue.main)
timer.scheduleRepeating(deadline: .now(), interval: .seconds(60))
timer.setEventHandler
{
NSLog("Hello World")
}
timer.resume()
This is specially useful for when you need to dispatch on a particular Queue. Also, if you're planning on using this for user interface updating, I suggest looking into CADisplayLinkas it's synchronized with the GPU refresh rate.
当您需要在特定队列上调度时，这特别有用。此外，如果您打算将其用于用户界面更新，我建议您查看CADisplayLink它是否与 GPU 刷新率同步。
