c11ada c11ada - 1 year ago 107
Swift Question

Completion Handlers in Swift

I'm fairly new at swift development and trying to get a handle on closures and completion handlers. I have a function with the following declaration inside a struct called ObjectData

func getData(id1:Int, id2:Int, completion: (dataObject? -> Void))

I am trying to call this function like

ObjectData.getData(1, id2: 2){
(let myObject) in

but i get the following error

Cannot invoke 'getData' with an argument list of type '(NSNumber, id2:
NSNumber, (_) -> _)'

Please can someone help

Answer Source

For better readability, change the header to this. Remember that you have to declare types, not variable names:

func getData(id1:Int, id2:Int, completion: (ObjectData?) -> (Void))

Now I personally use this syntax to use closures:

self.getData(1, id2: 1) { (data) -> (Void) in

     // Some code executed in closure

If you want to study further, you can find full syntax of closures here (notice appropriate name of the website). Hope it helps!

Recommended from our users: Dynamic Network Monitoring from WhatsUp Gold from IPSwitch. Free Download