如何用Swift语法编写这个Objective-C块？

Question

I recently switched from working with Objective-C to Swift and now I am facing the following objective-c block. I cannot figure out how to write it in Swift (1.2) syntax . This is how the block is defined in objective-c:

formatter = ^(CGFloat value){

            // do something with value

            return "stringrepresentation";
        };

Could someone be kind and show me the correct syntax?

ADDITIONAL Info: the "formatter" value needs to be of type ValueFormatter

How to achieve this?

Answer 1

That would look like this:

let formatter = { (value: CGFloat) -> String in
    // do something with value
    return "the formatted thing"
}

The type of formatter will be (CGFloat) -> String .

Answer 2

Look at closures .

{(/*Parameters*/) -> /*ReturnType*/ in
    // Statements
}

So this block would be:

{(value : CGFloat) -> String in
    // Do cool stuff
    retun "aString"
}

Answer 3

SWIFT 2

Block Declarations

var myCallBack:((Bool)->Void)? = nil

Block sending back

  self.myCallBack!(true)

Block Receiving back

myCallBack = { (isSuccess: Bool)-> () in
          //perform action you want to      
            }