SBJson 和 NSData

Question

我正在从 quizlet.com 获取数据，它适用于简单的代码：

-(void) grabbQuizletWithUrl:(NSURL*)requstURL {

     NSString *dataString = [NSString stringWithContentsOfURL:requestURL encoding:NSUTF8StringEncoding error:&error]; 

     NSDictionary *dict = [dataString JSONValue];
}

但我需要使用 NSURLConnection 来启动和停止活动指示器。我在努力

-(void) grabbQuizletWithUrl:(NSURL*)requstURL {

    NSURLRequest *quizletRequest = [[NSURLRequest alloc] initWithURL:requestURL];
    NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:quizletRequest
                                                          delegate:self];
    [connection release];
    [quizletRequest release];

}

// and getting data in delegate method:



- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

    [self.activityIndicator stopAnimating];

    NSString *dataString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

    NSDictionary *dict = [dataString JSONValue];

}

我收到这样的消息：

[2377:707] -JSONValue 失败。错误是：输入意外结束

[2377:707] -JSONValue 失败。错误是：令牌的非法开始 [.]

[2377:707] -JSONValue 失败。错误是：令牌[d]的非法开始

Answer 1

在- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data; 中，您应该将收到的数据附加到先前存储的数据中，因为您只得到了响应的一部分，即：

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    // someNSMutableDataIVar is an ivar to store the data in
    [someNSMutableDataIVar appendData:data];
}

然后在另一个名为 :- (void)connectionDidFinishLoading:(NSURLConnection *)connection; 的委托方法中，您应该处理数据。

-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
    // the connection finished loading all data, process...
    [self.activityIndicator stopAnimating];
    NSString *dataString = [[NSString alloc] 
                            initWithData:someNSMutableDataIVar
                                encoding:NSUTF8StringEncoding];
    NSDictionary *dict = [dataString JSONValue];
}

异步 ​​URL 加载系统在 Apple 的URL Loading System Programming Guide 中有详细描述。

希望这会有所帮助！