Question

我有以下两种方法：

-(void)authenticateUserToGoogle:(NSString *)userName withPassword:(NSString *)password {


    NSString *URLstr = GOOGLE_CLIENT_LOGIN;
    URLstr = @"http://www.google.com/ig/api?stock=AAPL";
    NSURL *theURL = [NSURL URLWithString:URLstr];
    NSURLRequest *theRequest = [NSURLRequest requestWithURL:theURL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:100.0];

    NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];

    if (!theConnection) {
        NSLog(@"COuldn't register device information with Parking Server");
    } else {
        NSLog(@"Got a connection!!");
        NSMutableData       *_responseData = [NSMutableData data];
        NSLog(@"respone_data = %@",_responseData);

    }
    }

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    NSHTTPURLResponse *HTTPResponse = (NSHTTPURLResponse *)response;
    NSInteger statusCode = [HTTPResponse statusCode];

    if (404 == statusCode || 500 == statusCode) {
        //[self.controller setTitle:@"Error Getting Parking Spot ....."];
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:FALSE];
        NSLog(@"GOT A 'FUCKED' STATUS CODE");

        [connection cancel];
        NSLog(@"Server Error - %@", [NSHTTPURLResponse localizedStringForStatusCode:statusCode]);
    } else if (200 == statusCode) {
        NSLog(@"GOT A 'OK' RESPONSE CODE");

    }

}

如果我将authenticateUserToGoogle方法称为这样的实例方法：

[self authenticateUserToGoogle:user withPassword:password]

我得到以下输出：

2011-08-12 00:14:08.490 stcoks[81272:f203] Got a connection!!
2011-08-12 00:14:08.492 stcoks[81272:f203] respone_data = <>
2011-08-12 00:14:08.726 stcoks[81272:f203] GOT A 'OK' RESPONSE CODE

但是，如果我将authenticateUserToGoogle方法更改为类方法，只需将方法签名中的“ - ”更改为“+”，然后将其调用为：

[MasterViewController authenticateUserToGoogle:user withPassword:password]

我得到以下输出：

2011-08-12 00:14:08.490 stcoks[81272:f203] Got a connection!!
2011-08-12 00:14:08.492 stcoks[81272:f203] respone_data = <>

换句话说，它似乎与类方法一样，委托方法连接didReceiveResponse永远不会被调用!!

任何人都可以向我解释这种行为吗？谢谢！

Answer 1

使用delegate:self启动NSURLConnection时，会设置将接收connection:didReceiveResponse:消息的委托对象。如果在类方法中使用self，则此方法也将作为类方法调用。

Answer 2

您在方法中将委托设置为self。如果它是类方法，则self不包含类的实例。我猜它可能是班级本身，也可能是零。

尝试将两者都更改为类方法。

Answer 3

如果您将authenticateUserToGoogle方法更改为类方法，只需将方法签名中的"-"更改为"+"，然后更改connection:didReceiveResponse:委托方法{{ 1}}到"-"。所以你的代码看起来像，

"+"

Answer 4

除非您还将委托方法更改为类方法，否则不会调用它，因为委托（类）不响应消息 - 只有它的实例才会响应。

Objective-C类方法不会在实例方法的情况下调用委托方法

4 个答案: