代理在AFNetworking响应块内变为零？

Question

我正在使用AFNetworking来获取数据，并且在Service类中有一个委托，该委托可以是UIController。 Service类负责通过AFNetworking类获取数据。

//Class Service. 


@interface Service : NSObject {

    __weak id<ServiceDelegate>delegate;

}


- (void) doFetch:(APIInput*) input {

    NSURL *url = [NSURL URLWithString:[self getLocation:input]];
    NSLog(@"url request is: %@", url);
    NSURLRequest *request = [NSURLRequest requestWithURL:url];

    AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        //NSLog(@"IP Address: %@", [JSON valueForKeyPath:@"origin"]);

        [self.delegate serviceDidComplete:[self allocNewData:JSON]];
    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response,
                NSError *error, id JSON){

        [self.delegate serviceFailed: error];
    }];

    [operation start];
}

在UIController viewDidLoad中：

self.networkService = [[Service alloc] init];
[self.networkService setDelegate:self];

一旦运行ios应用程序，self.delegate为零。 为什么会这样呢？

Answer 1

这解决了。 我在设置操作之前创建了一个__block变量

__block id itsme = self.delegate;

AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        //NSLog(@"IP Address: %@", [JSON valueForKeyPath:@"origin"]);

        [itsme serviceDidComplete:[self allocNewData:JSON]];
    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response,
                NSError *error, id JSON){

        [itsme serviceFailed: error];
    }];