dispatch_after - GCD in Swift?

Question

I\'ve gone through the iBook from Apple, and couldn\'t find any definition of it:

Can someone explain the structure of dispatch_after?

d         


        

Answer 1

Another helper to delay your code that is 100% Swift in usage and optionally allows for choosing a different thread to run your delayed code from:

public func delay(bySeconds seconds: Double, dispatchLevel: DispatchLevel = .main, closure: @escaping () -> Void) {
    let dispatchTime = DispatchTime.now() + seconds
    dispatchLevel.dispatchQueue.asyncAfter(deadline: dispatchTime, execute: closure)
}

public enum DispatchLevel {
    case main, userInteractive, userInitiated, utility, background
    var dispatchQueue: DispatchQueue {
        switch self {
        case .main:                 return DispatchQueue.main
        case .userInteractive:      return DispatchQueue.global(qos: .userInteractive)
        case .userInitiated:        return DispatchQueue.global(qos: .userInitiated)
        case .utility:              return DispatchQueue.global(qos: .utility)
        case .background:           return DispatchQueue.global(qos: .background)
        }
    }
}

Now you simply delay your code on the Main thread like this:

delay(bySeconds: 1.5) { 
    // delayed code
}

If you want to delay your code to a different thread:

delay(bySeconds: 1.5, dispatchLevel: .background) { 
    // delayed code that will run on background thread
}

---

If you prefer a Framework that also has some more handy features then checkout HandySwift. You can add it to your project via Carthage then use it exactly like in the examples above, e.g.:

import HandySwift    

delay(bySeconds: 1.5) { 
    // delayed code
}