FlineDev#11 Done

README.md

@@ -118,6 +118,18 @@ delay(by: .seconds(5), dispatchLevel: .userInteractive) {
 }
 ```
 
+#### every(_ interval:) { ... }
+Runs a given closure every interval. Dispatch queue can be set optionally (as well as QoS and allowed leeway, see definition)
+``` Swift
+var counter = 0
+let timer = every(.milliseconds(10)) {
+    counter += 1
+    print("I've been executed \(counter) times")
+}
+sleep(3)
+timer.cancel() // you must stop the execution manually (otherwise you may end up with zombie processes when killing the app manually), note that this cannot be done inside a closure
+```
+
 ### IntExtension
 
 #### init(randomBelow:)

Sources/Globals.swift

@@ -18,3 +18,26 @@ public func delay(by delayTime: Timespan, qosClass: DispatchQoS.QoSClass? = nil,
     let dispatchQueue = qosClass != nil ? DispatchQueue.global(qos: qosClass!) : DispatchQueue.main
     dispatchQueue.asyncAfter(deadline: DispatchTime.now() + delayTime, execute: closure)
 }
+
+/// Executes passed closure every Timespan interval.
+///
+/// - Parameters:
+///   - interval: Execution interval duration
+///   - queue: Dispatch queue for execution. Defaults to global
+///   - qos: Quality of service. Defaults to .default
+///   - leeway: Allowed leeway between executions. Defaults to .milliseconds(10)
+///   - closure: Block of code to run
+/// - Returns: Timer object
+public func every(
+    _ interval: Timespan,
+    queue: DispatchQueue = DispatchQueue.global(),
+    qos: DispatchQoS = .default,
+    leeway: DispatchTimeInterval = .milliseconds(10),
+    _ closure: @escaping DispatchSourceProtocol.DispatchSourceHandler
+) -> DispatchSourceTimer {
+    let timer = DispatchSource.makeTimerSource(queue: queue)
+    timer.setEventHandler(qos: qos, handler: closure)
+    timer.scheduleRepeating(deadline: .now(), interval: interval, leeway: leeway)
+    timer.resume()
+    return timer
+}

Tests/GlobalsTests.swift

@@ -23,4 +23,18 @@ class GlobalsTests: XCTestCase {
 
         waitForExpectations(timeout: delayTime + 1.0, handler: nil)
     }
+
+    func testEvery() {
+        let expectation = self.expectation(description: "Wait for three executions.")
+        var counter = 0
+        let timer = every(.milliseconds(10)) {
+            counter += 1
+            if counter >= 3 {
+                expectation.fulfill()
+            }
+        }
+        waitForExpectations(timeout: 2) { error in
+            timer.cancel()
+        }
+    }
 }