A timer sends a message to an object after a certain amount of time passes. Start by declaring a variable for the timer.
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var saveTimer = Timer() |
Starting a Timer
Call the scheduledTimer method to start a timer. The scheduledTimer method takes the following arguments:
- A time interval for how often the timer fires, specified in seconds.
- Target, which is the object that receives the message from the timer.
- Selector, which is the function the target should run after receiving the message.
- UserInfo, which is optional additional information you can send.
- Repeats, which indicates whether the timer runs once or repeats.
The following code starts a timer to autosave data every 30 seconds:
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func startTimer() { saveTimer = Timer.scheduledTimer(timeInterval: 30.0, target: self, selector: #selector(self.autosave), userInfo: nil, repeats: true) } |
The function for the selector needs @objc at the start of the declaration.
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@objc func autosave(timer: Timer) { <p>} |
Stopping a Timer
Call the invalidate method to stop a timer. The following code stops a timer:
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func stopTimer() { saveTimer.invalidate() } |