Typealias with closure

[javed]

Hi Team,

Basically this is the code i want to understand why typealias is used

typealias DownloadCountHandler = (Int)->()
var onDownloadFileCompleteCount : DownloadCountHandler?{
didSet{
if onDownloadFileCompleteCount != nil{

        }else{
            
        }
    }
}

i am calling initiallizing this as
if let onDownloadFileCompleteCount = self.onDownloadFileCompleteCount{
self.DownloadCompleteCount(completionHandler: onDownloadFileCompleteCount)
}
this code is fine but when i write the same code as
var onDownloadFileCompleteCount : (Int)->(){
didSet{
if onDownloadFileCompleteCount != nil{

        }else{
            
        }
    }
}

and then i am calling initiallizing this as
if let onDownloadFileCompleteCount = self.onDownloadFileCompleteCount{
self.DownloadCompleteCount(completionHandler: onDownloadFileCompleteCount)
}
and the i am getting error as Initializer for conditional binding must have Optional type, not ‘(Int) → ()’

[jayantvarma]

Hi @javed,
Typealias is a way to make the code readable, instead of typing (Int) -> () or (Int) -> Void again and again, it is easier and readable as DownloadCountHandler

And the second part of your question,

In the first example you are using

var onDownloadFileCompleteCount : DownloadCountHandler?{

where as in the second example you are using

var onDownloadFileCompleteCount : (Int)->(){

The function is an optional, but you are not declaring it as an optional in your interpretation. You need to use

var onDownloadFileCompleteCount : ((Int)->())? {

then it will all good,
cheers,