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

Vector graphics in iOS

In past, designers had to create multiple versions of the same asset (1x, 2x, 3x) to satisfy multiple screen sizes. Using vector assets can save you time because you only have to generate the asset once. You just need an.xcassets file in your project for storing your images. In there, you can declare image sets to be “Vectors”.
A vector file contains a lot of metadata of an asset that tells the system how to render it's contents, independent of the screen's resolution. This also means that whenever we get larger screen resolutions, Xcode will be able to scale up your images from your already existing vector PDF for you, giving you automatic support for future devices for free.

Steps:-
Select “New Image Set” in your XCAsset.Select the Attributes Inspector in Utilities panel.Under the types drop-down menu, select "Vector"Drag and drop your vector PDFUse the Xcode image catalog image set as you would with any other image. For instance, calling --imageNamed: in code, and pa…

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.