URL File Size With NSURLConnection - Swift - ios

Question

i am trying to get a file size from url before downloading
here is the obj-c code
NSURL *URL = [NSURL URLWithString:"ExampleURL"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
[request setHTTPMethod:#"HEAD"];
NSHTTPURLResponse *response;
[NSURLConnection sendSynchronousRequest:request returningResponse:&response error: nil];
long long size = [response expectedContentLength];
and here is Swift Code
var url:NSURL = NSURL(string: "ExmapleURL")
var request:NSMutableURLRequest = NSMutableURLRequest(URL: url)
request.HTTPMethod = "HEAD"
var response = NSHTTPURLResponse()
NSURLConnection.sendSynchronousRequest(request, returningResponse: &response , error: nil)
but i have error here
NSURLConnection.sendSynchronousRequest(request, returningResponse: &response , error: nil)
'NSHTTPURLResponse' is not identical to 'NSURLResponse?'
did i miss something in swift here ?

Answer 1

The response parameter has the type
AutoreleasingUnsafeMutablePointer<NSURLResponse?>
which means that you can pass the address of an optional NSURLResponse as argument:
var response : NSURLResponse?
NSURLConnection.sendSynchronousRequest(request, returningResponse: &response , error: nil)
You can then conditionally cast the returned response to a NSHTTPURLResponse:
if let httpResponse = response as? NSHTTPURLResponse {
println(httpResponse.expectedContentLength)
}
Note that you should check the return value of sendSynchronousRequest(), which
is nil if no connection could be made.
It is also recommended to call this
method only from a separate thread (or use sendAsynchronousRequest() instead)
because it can take a while to make a connection
– in particular when using a cellular network – and the main thread would be
blocked otherwise.

Answer 2

Swift 4 solution:
func fetchContentLength(for url: URL, completionHandler: #escaping (_ contentLength: Int64?) -> ()) {
var request = URLRequest(url: url)
request.httpMethod = "HEAD"
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
guard error == nil, let response = response as? HTTPURLResponse, let contentLength = response.allHeaderFields["Content-Length"] as? String else {
completionHandler(nil)
return
}
completionHandler(Int64(contentLength))
}
task.resume()
}
// Usage:
let url = URL(string: "https://s3.amazonaws.com/x265.org/video/Tears_400_x265.mp4")!
fetchContentLength(for: url, completionHandler: { contentLength in
print(contentLength ?? 0)
})