How to run code after a delay using asyncAfter() and perform()
Swift version: 5.1
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.
So, using GCD we can write something that runs code after a half-second delay:
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.
To call the authenticate() method after 1 second, you would use this code:
perform(#selector(authenticate), with: nil, afterDelay: 1)Note: any method called using perform(_:with:afterDelay:) must be marked with the @objc attribute.
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Available from iOS 4.0
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