Why in swift we cannot adopt a protocol without inheritance a class from NSObject?

Question

If i use the following code it shows me error "Type 'HttpConnection' does not conform to protocol 'NSObjectProtocol'"

class HttpConnection : NSURLConnectionDataDelegate {         var urlConnection       : NSURLConnection?         weak var delegate       : HttpConnecting?          init(delegate:HttpConnecting){             self.delegate = delegate;         }          func startAsynRequestWithUrlString(url:NSString, withMethod:NSString){         }     } 

If i subclass HttpConnection to NSObject then it works fine. So my question is when i need to adopt NSURLConnectionDataDelegate protocol in swift why i need to inherit the class from NSObject?

Answer 1

NSURLConnectionDataDelegate itself inherits from NSURLConnectionDelegate which inherits from NSObjectProtocol.

That means that apart from implementing all the methods from NSURLConnectionDataDelegate, and NSURLConnectionDelegate, you also have to implement all the methods from NSObjectProtocol (e.g. equality, hash).

You didn't implement them, that's your mistake. If you inherit from NSObject, all that NSObjectProtocol methods are already implemented for you.