Closure is not constructible with - xcode

Question

I am practicing Swift and I have the following code:
import Foundation
#objc class Model {
typealias completionBlock = (data: NSData?, error: NSError?) -> Void
func saveEmailAccount(email: String, password: String, mailServer: String, mailPort: Int, completionHandler: completionBlock) -> Void {
let httpPOSTBody = ["email" : email, "password" : password, "mailServer" : mailServer, "mailPort" : mailPort]
let urlRequest = NSMutableURLRequest()
urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
urlRequest.addValue("application/json", forHTTPHeaderField: "Accept")
urlRequest.HTTPMethod = "POST"
urlRequest.HTTPBody = NSJSONSerialization.dataWithJSONObject(httpPOSTBody, options: nil, error: nil)
let session = NSURLSession(configuration: NSURLSessionConfiguration.defaultSessionConfiguration())
session.dataTaskWithURL(urlRequest.URL!, completionHandler: { (data: NSData!, response:NSURLResponse!, error: NSError!) -> Void in
completionBlock(data, error)
})
}
}
But I am getting "completionBlock is not constructible with '(NSData!, NSError!)'. Not sure what I'm doing wrong

Answer 1

You're trying to invoke completionHandler with the typo completionBlock Change the block invocation from:
completionBlock(data, error)
to:
completionHandler(data, error)
One reason why Apple suggests (and I concur) that type names should start with caps and variable names with lower case.
The other problem is that by defining the type alias as:
typealias completionBlock = (data: NSData?, error: NSError?) -> Void
You are specifying that the completion block should be defined and called with named parameters:
completionHandler(data:data, error:error)
Or, change the type alias to:
typealias completionBlock = (NSData?, NSError?) -> Void
Which would be more inline with the norms I've seen.