Skip to main content

Blocks in SWIFT 3 and SWIFT 2

SWIFT 3

//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))){
            self.handler_DepatureCityAction?(sender)
        }

    }

//View controller where you want callback

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

SWIFT 2

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

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


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


///*** ******BLOCK WITH PARAMETER

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

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

Comments

Popular posts from this blog

Play youtube video in iOS app

Youtube video can be played in iOS app using webview. MPMoviePlayerController is not able to open youtube video automatically. Integrate the below script to show thumbnail, clicking on it the video will play in full screen.


NSString *url = @"https://www.youtube.com/embed/8aMHGC6A5zc"; NSString* embedHTML = @"\     <html><head>\     <style type=\"text/css\">\     body {\     background-color: transparent;\     color: white;\     }\     </style>\     </head><body style=\"margin:0\">\     <iframe id=\"yt\" src=\"%@\" type=\"application/x-shockwave-flash\" \     width=\"%0.0f\" height=\"%0.0f\" frameborder=\"0\" feature=player_detailpage allowfullscreen></iframe>\     </body></html>"; NSString* html = [NSStringstringWithFormat:embedHTML, url, self.view.frame.size.width, 200.0];
    [webviewloadHTMLString:html baseURL:nil];


///*******************A…

Disabling print for Production In Swift Project

You'll need to set up a compiler flag to use the Swift preprocessor - go to the Swift Compiler - Custom Flags section of Build Settings to set up a -D DEBUG flag:



Then in your code you can define a DLog() function and only print your message if the DEBUG flag is set:
func DLog(message: String, function: String = __FUNCTION__) { #if DEBUG     println("\(function): \(message)") #endif }

Return multiple values from a function in objective C

We can return tuples in swift as follows:-

func getData()->(Int,Int,Int){//...code herereturn( hour, minute, second)}You can't do that in objective-c. Best option is using parameters by reference. Something like this.