objective-c - 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 来启动和停止事件指示器。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:意外的输入结束

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

[2377:707] -JSONValue 失败。错误是: token [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追加到先前存储的数据中，因为您只得到了一部分响应，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(delegate)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 URL Loading System Programming Guide 中有详细描述。来自苹果。

希望对您有所帮助!