CODEWITHSUNDEEP
swiftclosurescompletionhandler
c11ada
c11ada

Reputation: 4334

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

Upvotes: 3

Views: 1301

Answers (4)

Lineesh K Mohan
Lineesh K Mohan

Reputation: 1712

In SWIFT 3,It is known as completion closure.

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

    //Do the stuff before calling completion closure
    completion(value as? dataObject)   
}

ObjectData.getData(id1:1, id2: 2,completion:{(data) -> (Void) in
    //Do the completion stuff here
}

Upvotes: 0

maxpovver
maxpovver

Reputation: 1600

Far away from my Mac now, so I can't test, but try this:

ObjectData.getData(1, id2: 2, (dataObject) -> { 
...code...
});

Also can't check now, but I think this also should work:

    ObjectData.getData(1, id2: 2)(dataObject){ 
...code...
}

Upvotes: 1

Jiri Trecak
Jiri Trecak

Reputation: 5122

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!

Upvotes: 4

Kristijan Delivuk
Kristijan Delivuk

Reputation: 1252

try to initialize your class first (ex. var objectData = ObjectData()) , and then call function with objectData.getData... it should work that way ..

Upvotes: 0

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