Keyless Swift class with closure: syntactic sugar or something else?

Question

I am trying to understand why I can omit the parentheses in the initialization of the class when it takes a block as a parameter.

An example without brackets:

var block = CCActionCallBlock { () -> Void in
    NSLog("sedfjsdkl")
}

And here is the formally correct version with brackets:

var block = CCActionCallBlock ( { () -> Void in
    NSLog("sedfjsdkl")
})

Both options work as expected, there are no runtime errors or compiler warnings.

In what circumstances can I omit the class initializer brackets? Is this the same code or does it have any side effects? Are there any other syntactic sugars regarding closures / blocks that I should be aware of?

Note. I know that a closure as the last parameter can be written after brackets, but cannot find anything related to the absence of brackets.

, , , / :

var block = MyClass   // error, obviously ...

Update: -, Xcode .

Answer 1

Closures Swift ( ):

, () , .