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Blocks in SWIFT 3 and SWIFT 2


//Custom view/cell say LocationPickerView (: UIView)

typealias blockDefination_DepatureCityAction = (_ button : UIButton) -> Void

var handler_DepatureCityAction:blockDefination_DepatureCityAction?

@IBAction func btnDepatureCityAction(_ sender: UIButton) {
        if(self.responds(to: #selector(getter: LocationPickerView.handler_DepatureCityAction))){


//View controller where you want callback

let locationPickerObject = LocationPickerView(frame: viewLocation.bounds)
locationPickerObject.handler_DepatureCityAction = { button in
            print("DepatureCityAction in view controller")


//**************** BLOCK WITHOUT PARAMETER

//DECLARE as property
  • typealias completionBlockSeeMore = () -> Void
  • var cMoreButtonCallBack:completionBlockSeeMore?
  • if(self.respondsToSelector("cMoreButtonCallBack")){             self.cMoreButtonCallBack!() }

  • cell.cMoreButtonCallBack = { () -> Void in
                    printf("Callback in block")


  • typealias completionBlockSeeMore = (sender: UIButton) -> Void
  • var cMoreButtonCallBack:completionBlockSeeMore?
  • if(self.respondsToSelector("cMoreButtonCallBack")){ self.cMoreButtonCallBack!(sender: sender) }

  •   cell.cMoreButtonCallBack = { (sender: UIButton) -> Void in
                    print("callback in block \(sender)")


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