完成块的返回结果 [英] Return Result of Completion Block

问题描述

所以我正在尝试在项目的Twitter API（以及其他）之上构建一个层，我需要找到一种方法将Twitter操作的结果返回到抽象层。

So I'm trying to build a layer on top of the Twitter API (among others) for a project and I need to find a way to return the result of the Twitter actions to the layer of abstraction.

现在我的设置是这样的，例如：

Right now my setup is something like this, for example:

-(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'我最后一行导致错误。

But because the 'performRequestWithHandler:' method returns 'void' I the final line causes an error.

我也尝试将'return'语句放在块之外并锁定执行发现本文后的代码块部分： http://omegadelta.net/2011/05/10/how-to-wait-for-ios-methods-with-completion-blocks-to-finish

I've also tried placing the 'return' statement outside of the block and locking the execution of the block section of code after discovering this article: http://omegadelta.net/2011/05/10/how-to-wait-for-ios-methods-with-completion-blocks-to-finish

仍然没有运气。

我希望有人可以通过这种方式解决这个问题（或者建议更好的方法）返回数据）。

I hope someone can shed some light on this way to do it (or perhaps suggest a better method to return the data).

推荐答案

为什么不使用块来返回响应？类似于：

Why don't you also use a block to return the response? Something like:

-(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);
    }];
}

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