Writing handler for UIAlertAction

Question

I m presenting a UIAlertView to the user and I can t figure out how to write the handler  This is my attempt   let alert   UIAlertController title   Title                               message   Message                        preferredStyle  UIAlertControllerStyle Alert   alert addAction UIAlertAction title   Okay                                 style  UIAlertActionStyle Default                              handler   self in println  Foo       I get a bunch of issues in Xcode   The documentation says convenience init title title  String   style style  UIAlertActionStyle  handler handler    UIAlertAction   - gt  Void     The whole blocks closures is a little over my head at the moment  Any suggestion are much appreciated

User · Answer

Syntax change in swift 3 0  alert addAction UIAlertAction title   Okay                   style   default                  handler      in print  Foo

User · Answer

this is how i do it with xcode 7 3 1     create function func sayhi      print  hello          create the button   let sayinghi   UIAlertAction title   More   style  UIAlertActionStyle Default  handler     action in             self sayhi          adding the button to the alert control  myAlert addAction sayhi        the whole code  this code will add 2 buttons      IBAction func sayhi sender  AnyObject            let myAlert   UIAlertController title   Alert   message  sup   preferredStyle  UIAlertControllerStyle Alert           let okAction   UIAlertAction title   OK   style  UIAlertActionStyle Default  handler nil           let sayhi   UIAlertAction title   say hi   style  UIAlertActionStyle Default  handler     action in             self sayhi                 this action can add to more button         myAlert addAction okAction           myAlert addAction sayhi            self presentViewController myAlert  animated  true  completion  nil             func sayhi               move to tabbarcontroller      print  hello

User · Answer

In Swift 4    let alert UIAlertController title  someAlert   message   someMessage   preferredStyle UIAlertControllerStyle alert    alert addAction UIAlertAction title   ok   style  UIAlertActionStyle default  handler              in print  FOO         present alert  animated  true  completion  nil

User · Answer

Functions are first-class objects in Swift  So if you don t want to use a closure  you can also just define a function with the appropriate signature and then pass it as the handler argument  Observe   func someHandler alert  UIAlertAction            Do something       alert addAction UIAlertAction title   Okay                                 style  UIAlertActionStyle Default                                handler  someHandler

User · Answer

Instead of self in your handler  put  alert  UIAlertAction    This should make your code look like this       alert addAction UIAlertAction title   Okay                             style  UIAlertActionStyle Default                          handler    alert  UIAlertAction   in println  Foo        this is the proper way to define handlers in Swift   As Brian pointed out below  there are also easier ways to define these handlers  Using his methods is discussed in the book  look at the section titled Closures

User · Answer

In Swift  let alertController   UIAlertController title  Title   message   Message   preferredStyle  alert   let Action   UIAlertAction init title   Ok   style   default     UIAlertAction  in        Write Your code Here    alertController addAction Action  self present alertController  animated  true  completion  nil   In Objective C  UIAlertController  alertController    UIAlertController alertControllerWithTitle   Title  message   Message  preferredStyle UIAlertControllerStyleAlert    UIAlertAction  OK    UIAlertAction actionWithTitle   OK  style UIAlertActionStyleDefault handler   UIAlertAction    Nonnull action          alertController addAction OK     self presentViewController alertController animated YES completion nil

User · Answer

create alert  tested in xcode 9  let alert   UIAlertController title   title   message   message   preferredStyle  UIAlertControllerStyle alert  alert addAction UIAlertAction title   Ok   style  UIAlertActionStyle default  handler  self finishAlert   self present alert  animated  true  completion  nil    and the function   func finishAlert alert  UIAlertAction

User · Answer

Lets assume that you want an UIAlertAction with main title  two actions  save and discard  and cancel button   let actionSheetController   UIAlertController  title   My Action Title   message      preferredStyle  UIAlertControllerStyle ActionSheet         Add Cancel-Action     actionSheetController addAction UIAlertAction title   Cancel   style  UIAlertActionStyle Cancel  handler  nil          Add Save-Action     actionSheetController addAction UIAlertAction title   Save   style  UIAlertActionStyle Default  handler     actionSheetController  - gt  Void in         print  handle Save action                     Add Discard-Action     actionSheetController addAction UIAlertAction title   Discard   style  UIAlertActionStyle Default  handler     actionSheetController  - gt  Void in         print  handle Discard action                      present actionSheetController     presentViewController actionSheetController  animated  true  completion  nil    This works for swift 2  Xcode Version 7 0 beta 3

User · Answer

You can do it as simple as this using swift 2   let alertController   UIAlertController title   iOScreator   message           Hello  world    preferredStyle  UIAlertControllerStyle Alert  alertController addAction UIAlertAction title   Dismiss   style  UIAlertActionStyle Destructive handler    action in         self pressed        func pressed         print  you pressed            or     let alertController   UIAlertController title   iOScreator   message           Hello  world    preferredStyle  UIAlertControllerStyle Alert  alertController addAction UIAlertAction title   Dismiss   style  UIAlertActionStyle Destructive handler    action in       print  pressed          All the answers above are correct i am just showing another way that can be done

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