Question

我需要在两个搜索引擎中实现同步搜索。我有两个功能： * - （void）searchYoutube：（NSString ）text 和 * - （void）searchYahoo：（NSString ）text

(void) searchYahoo:(NSString *)text{

   NSString *urlString = [NSString stringWithFormat:@"http://search.yahooapis.com/WebSearchService/V1/webSearch?appid=%@&output=json&query=%@&results=30", YahooAppId, text];
NSLog(@"URL zaprosa: %@",urlString);

//Create NSURL string from formatted string
NSURL *url = [NSURL URLWithString:urlString];


NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
NSURLConnection *connection = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
if (connection)
{
    NSLog(@"Data will be received from URL: %@", url);
}
else
{
    NSLog(@"Data couldn't be received from URL: %@", url);
}}

功能-searchYoutube：与上面类似。但是当我用这两个函数调用查询时，我看到了

2011-06-26 14:06:27.523 TrueSearcher[5373:207] URL query: http://gdata.youtube.com/feeds/api/videos?q=os&start-index=1&max-results=30&alt=jsonc&v=2
2011-06-26 14:06:27.874 TrueSearcher[5373:207] Data will be received from URL: http://gdata.youtube.com/feeds/api/videos?q=os&start-index=1&max-results=30&alt=jsonc&v=2
2011-06-26 14:06:27.875 TrueSearcher[5373:207] URL query: http://search.yahooapis.com/WebSearchService/V1/webSearch?appid=jwGJkT32&output=json&query=os&results=30
2011-06-26 14:06:29.010 TrueSearcher[5373:207] Data will be received from URL: http://search.yahooapis.com/WebSearchService/V1/webSearch?appid=jwGJkT32&output=json&query=os&results=30

就是这样。我收不到任何数据。我做错了什么？

Answer 1

好吧，

 NSURLConnection *connection = [NSURLConnection 
    sendSynchronousRequest:request returningResponse:nil error:nil];

错了。 sendSynchronousRequest会返回带有响应数据的(NSData *)。所以，一个更正确的方法来做你想要的是

  NSData *responseData = [NSURLConnection 
    sendSynchronousRequest:request returningResponse:nil error:nil];

然后您阅读responseData的回复。

您还应该查看NSURLConnection的文档。

Answer 2

这不是答案，而是提高绩效的建议，答案已经由uvesten提供。

sendSynchronousRequest不是一种好的实现方式，它不会在请求完成之前离开控件，所以如果加载需要时间，app就不会响应触摸。

相反，您可以尝试

NSString *urlString = [NSString stringWithFormat:@"http://search.yahooapis.com/WebSearchService/V1/webSearch?appid=%@&output=json&query=%@&results=30", YahooAppId, text];
NSLog(@"URL zaprosa: %@",urlString);

//Create NSURL string from formatted string
NSURL *url = [NSURL URLWithString:urlString];


NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
[[NSURLConnection alloc] initWithRequest:request delegate:self];

并实现委托方法

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
    expectedSize = [response expectedContentLength];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    if (objData==nil) { 
        objData = [[NSMutableData alloc] init]; 
    }
    [objData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
}

NSURLConnection sendSynchronousRequest的问题

2 个答案: