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How to run code after a delay using asyncAfter() and perform()

Paul Hudson       @twostraws

There are two ways to run code after a delay using Swift: GCD and perform(_:with:afterDelay:), but GCD has the advantage that it can run arbitrary blocks of code, whereas the perform() method runs methods.

DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
    // your code here
}

An alternative option is to use perform(_:with:afterDelay:), which lets you specify a method to call after a certain time has elapsed – and helpfully that time is specified in seconds, which makes it easier to remember!

To call the yourCodeHere() method after 1 second, you would use this code:

perform(#selector(yourCodeHere), with: nil, afterDelay: 1)

Available from iOS 4.0

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