objective-c - 完成 block 的返回结果

Question

因此，我正尝试在 Twitter API(以及其他)之上为一个项目构建一个层，我需要找到一种方法将 Twitter 操作的结果返回到抽象层。

现在我的设置是这样的，例如:

-(NSDictionary *)sendTweet:(Tweet *)tweet {
        __block NSMutableDictionary *responseDictionary;

    NSLog(@"Sending tweet");

    NSMutableDictionary *twitterRequestDictionary = [[NSMutableDictionary alloc] init];
    [twitterRequestDictionary setObject:tweet.tweetBody forKey:@"status"];

    TWRequest *request = [[TWRequest alloc] initWithURL:[NSURL URLWithString:@"https://api.twitter.com/1/statuses/update.json"]
                                             parameters:twitterRequestDictionary
                                          requestMethod:TWRequestMethodPOST];
    [request setAccount:self.userAccount];


    [request performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
        responseDictionary  = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableContainers error:nil];
        NSLog(@"Response dictionary: %@", responseDictionary);
        return responseDictionary;
    }];

但是因为“performRequestWithHandler:”方法返回“void”，最后一行导致错误。

在发现这篇文章后，我还尝试将“return”语句放在 block 外并锁定代码块部分的执行:http://omegadelta.net/2011/05/10/how-to-wait-for-ios-methods-with-completion-blocks-to-finish

仍然没有运气。

我希望有人能阐明这种方法(或者可能建议一种更好的方法来返回数据)。

Answer 1

为什么不也使用 block 来返回响应？像这样的东西:

-(void)sendTweet:(Tweet *)tweet withResponseCallback:(void (^)(NSMutableDictionary *responseDictionary))callback {

    NSLog(@"Sending tweet");

    NSMutableDictionary *twitterRequestDictionary = [[NSMutableDictionary alloc] init];
    [twitterRequestDictionary setObject:tweet.tweetBody forKey:@"status"];

    TWRequest *request = [[TWRequest alloc] initWithURL:[NSURL URLWithString:@"https://api.twitter.com/1/statuses/update.json"]
                                             parameters:twitterRequestDictionary
                                          requestMethod:TWRequestMethodPOST];
    [request setAccount:self.userAccount];


    [request performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
        NSMutableDictionary *responseDictionary  = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableContainers error:nil];
        NSLog(@"Response dictionary: %@", responseDictionary);
        callback(responseDictionary);
    }];
}