NSURLSession dataTaskForRequest:completion: unrecognized selector sent to instance

问题:

When trying to create my own session object NSURLSession() and request an url I get an unrecognized selector exception but when I use the shared session NSURLSession.sharedSession() everything works fine. How come?

var url = NSURL(string: "http:/www.google.com") if url != nil {     //throws unrecognized selector when dataTaskWithURL is called     let session=NSURLSession()     session.dataTaskWithURL(url!)     //works     let sharedSession=NSURLSession.sharedSession()     sharedSession.dataTaskWithURL(url!) } 

回答1:

You have to init URLSession with a configuration:

URLSession(configuration: .default) 

or use shared session

URLSession.shared 

回答2:

In SWIFT 3.0 and up:

        URLSession.shared.dataTask(with: url, completionHandler:         {             (data, response, error) in              //Your code         }).resume() 

回答3:

Aside from the shared session NSURLSession must be initialized with one of these two methods

init(configuration configuration: NSURLSessionConfiguration)   init(configuration configuration: NSURLSessionConfiguration,                delegate delegate: NSURLSessionDelegate?,              delegateQueue queue: NSOperationQueue?) 

回答4:

Do the initialization while declaration :-

var session = URLSession(configuration: .default) 

文章来源: NSURLSession dataTaskForRequest:completion: unrecognized selector sent to instance