ios - 在 block 内返回 BOOL 方法？

Question

我有一个 bool 方法，它为输入的字符串返回是或否。我成功地能够返回 YES 或 NO，但我似乎无法建立网络连接并返回 YES 或NO 取决于服务器的响应。我尝试使用 __block 并且我不觉得它会等待网络请求完成，有没有办法返回 YES 或 NO 在成功 block 中没有给我错误:

Incompatible block pointer types sending 'BOOL(^)(NSURLSessionTask*__strong, NSError __strong' to parameter of the type 'void(^)(NSURLSessionTask...)

-(BOOL)customResponseForString:(NSString *)text {

  __block BOOL response_available;

  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
    manager.responseSerializer = [AFHTTPResponseSerializer serializer];
    [manager.responseSerializer setAcceptableContentTypes:[NSSet setWithObject:@"text/plain"]];
    [manager GET:[NSString stringWithFormat:@"http://example.com/response.php?input=%@", text] parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {

        NSDictionary *response = [NSJSONSerialization JSONObjectWithData:responseObject options:NSUTF8StringEncoding error:nil];
        response_available = (BOOL)response[@"response_available"];
        if (response_available) {
            [session sendTextSnippet:response[@"response"] temporary:NO scrollToTop:NO dialogPhase:@"Summary"];
        } else {
            response_available = NO;
        }

        [session sendTextSnippet:[[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding] temporary:NO scrollToTop:NO dialogPhase:@"Summary"];

        [session sendRequestCompleted];

    } failure:^(NSURLSessionDataTask *task, NSError *error) {
        //return NO;
    }];
 });

return response_available;

}

Answer 1

您的 block 定义语法可能是错误的，因为您肯定可以在 block 中返回一个 BOOL 以及其他参数。

- (void)fetchCurrentUserWithCompletion:(void (^)(BOOL success, User *user))completion;

这个方法会这样调用:

[self.userProfileController fetchCurrentUserWithCompletion:^(BOOL success, User *user) {
    if (success) {
        NSLog(@"Current User Name: %@", user.fullName);
    }
}];

如果您使用 AFNetworking，请检查处理 completionBlocks 的 AFHTTPRequestOperation 对象:

[requestOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    User *user = [self userFromResponseObject:responseObject];   
    if (completion) completion(YES, user);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    if (completion) completion(NO, user);
}];