无法在 NSURLSession 中使用自定义委托

Question

我有一个 NSURLconnection 实现，并正在尝试迁移到 IOS-9 的 NSURlsession。

NSURL 连接实现：

@property (nonatomic, strong, readwrite) NSURLConnection *  connection;    

自定义委托方法：

-(BOOL)connection:(NSURLConnection *)connection ---canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace*)protectionSpace   
-(void)connection:(NSURLConnection *)connection  didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge  
- (void)connection:(NSURLConnection *)conn didReceiveResponse:(NSURLResponse *)aresponse  
-(void)connection:(NSURLConnection *)conn didReceiveData:(NSData *)data  
- (void)connectionDidFinishLoading:(NSURLConnection *)conn
- (void)connection:(NSURLConnection *)theConnection didFailWithError:(NSError*)error  

self.connection = [NSURLConnection connectionWithRequest:request delegate:self];

现在当我将上面的 impl 修改为基于 NSURLsession 的 impl 时，我现在有了

@property (nonatomic, strong, readwrite) NSURLSession *session;  

自定义委托方法：

- (BOOL)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace*)protectionSpace  
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge  
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didReceiveResponse:(NSURLResponse *)aresponse  
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didReceiveData:(NSData *)data   
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task connectionDidFinishLoading:(NSURLConnection *)conn  
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didFailWithError:(NSError *)error  


NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration    defaultSessionConfiguration];
self.session = [NSURLSession sessionWithConfiguration:configuration                                                                  delegate:self                                                                    delegateQueue: nil];
NSURLSessionDataTask *task = [self.session dataTaskWithRequest:request];
[task resume]; 

在这之后，我得到如下编译错误：

./../source/smmacosx/smplt.m:663:33: error: sending     'SmHttpsAuthenticationHandler *' to parameter of incompatible type 'id<NSURLSessionDelegate> _Nullable' [-Werror]

                                                                                                                           delegate: self

                                                                                                                                   ^~~~

 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS9.0.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSURLSession.h:135:132: note: 

      passing argument to parameter 'delegate' here

 + (NSURLSession *)sessionWithConfiguration:(NSURLSessionConfiguration   *)configuration delegate:(nullable id <NSURLSessionDelegate>)delegate delegateQueue:(nullable NSOperati...

我不明白为什么 NSURLSession Impl 中的 delegate=self 会抛出这样的错误？ SmHttpsAuthenticationHandler 是一个接口定义为

 @interface SmHttpsAuthenticationHandler: NSObject{....} and then   @implementation SmHttpsAuthenticationHandler

请帮助。请提供有关 NSURLSession 实现的任何指示。 非常感谢。

Answer 1

在你的接口声明中，你需要声明你的类符合 NSURLSessionDelegate 协议，例如

@interface SmHttpsAuthenticationHandler : NSObject