Completion Handler Example in Swift

completionHandler.swift

    var src: String = ""
    var completionHandler: ((_ success: Bool, _ outputURL: URL?)->())?
    
    var outputURL: URL?
    
    init(src: String, completion: ((_ success: Bool, _ outputURL: URL?) -> Void)? = nil) {
        super.init()
        
        self.src = src        
        self.completionHandler = completion
        
    }
    
    func finished(completed: Bool) {
        if completed {
            completionHandler!(true, outputURL)
        } else {
            completionHandler?(false, nil)
        }
    }