ios:带有返回值的 NSURLRequest 的方法

Question

我有一个向 api 发出特定请求的方法，我想从中返回结果。这是我的方法:

-(NSDictionary *) getProfileDataForUser:(NSString *)user_id {
NSURL *getProfileDataRequestURL = [NSURL URLWithString:[NSString stringWithFormat:@"%@users/profile.php?user_id=%@", _apiRootUrl, user_id]];
NSMutableURLRequest *getProfileDataRequest = [NSMutableURLRequest requestWithURL:getProfileDataRequestURL cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:10.0f];
[getProfileDataRequest setHTTPMethod:@"GET"];
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:getProfileDataRequest queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
    error = nil;
    id jsonData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];
    if (jsonData != nil && error == nil) {
        NSDictionary *responseDict = jsonData;
        if ([responseDict objectForKey:@"user"]) {
            // this is a dictionary
            return [responseDict objectForKey:@"user"];
        } else {
            return responseDict;
        }
    }
    else {
        return @{};
    }
}];

问题是我遇到了多个语义问题:

sendAsynchronousRequest 方法出错:

Incompatible block pointer types sending 'id (^)(NSURLResponse *__strong, NSData *__strong, NSError *__strong)' to parameter of type 'void (^)(NSURLResponse *__strong, NSData *__strong, NSError *__strong)'

返回错误:

Return type 'NSDictionary *' must match previous return type 'id' when block literal has unspecified explicit return type

我已经尝试将我的方法的返回类型更改为 id，并且只返回 jsonData 但我仍然遇到第一个语义问题。我怎样才能使它工作？

Answer 1

url 请求是异步的，因此该方法需要使用 block /回调来返回结果:

- (void) getProfileDataForUser:(NSString *)user_id withCallback:(void (^)(NSDictionary *jsonData))callback {
    NSURL *getProfileDataRequestURL = [NSURL URLWithString:[NSString stringWithFormat:@"%@users/profile.php?user_id=%@", _apiRootUrl, user_id]];
    NSMutableURLRequest *getProfileDataRequest = [NSMutableURLRequest requestWithURL:getProfileDataRequestURL cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:10.0f];
    [getProfileDataRequest setHTTPMethod:@"GET"];
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    [NSURLConnection sendAsynchronousRequest:getProfileDataRequest queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
        error = nil;
        id jsonData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];
        callback(jsonData);
    }];
}