NSURLConnection需要NSRunLoop才能执行？

Question

我正在尝试从名为connect的方法中获取URL的内容.它读取其配置设置并尝试获取URL.它似乎需要运行循环来执行.我虽然只执行一次并完成.似乎除了每次获取此URL时,无论何时调用connect,我都不需要运行该循环.有没有更好的方法呢？

- (BOOL) connect 
{
    // read serverName and eventId from preferences
    NSMutableArray* preferences;
    preferences = [NSMutableDictionary dictionaryWithContentsOfFile:@"/tmp/wt.plist"];

    // if these values aren't nil or blank
    if ([preferences valueForKey:@"serverAddress"] && [preferences valueForKey:@"eventId"]) {

        [self setServerAddress:@"172.16.28.210"];
        [self setEventId:@"OT-3037009"];
    } else{
        // return some kind of error message
    }

    NSLog(@"VideoDataURL: %@", [self getVideoDataURL]);

    // grab the URL and query the server

    NSURL *myURL = [NSURL URLWithString:@"http://localhost"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:myURL
                                                           cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
                                                       timeoutInterval:2];

    __unused NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];

    [[NSRunLoop currentRunLoop] run];

    return TRUE;
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    // This method is called when the server has determined that it
    // has enough information to create the NSURLResponse.

    // It can be called multiple times, for example in the case of a
    // redirect, so each time we reset the data.

    // receivedData is an instance variable declared elsewhere.
    [incomingData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    /* 
     * Called each time a chunk of data arrives
     */

    NSLog(@"received %lu bytes", [data length]);

    // Create a mutable data if it doesn't already exist
    if (!incomingData) {
        incomingData = [[NSMutableData alloc] init];
    }

    [incomingData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 
{
    /*
     * Called if the connection fails
     */

    NSLog(@"connection failed: %@", [error localizedDescription]);  
    incomingData = nil;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection 
{
    /*
     * Called when the last chunk has been processed
     */

    NSLog(@"Got it all!");

    NSString *string = [[NSString alloc] initWithData:incomingData encoding: NSUTF8StringEncoding];

    incomingData = nil;

    NSLog(@"response is: %@", string);
}

Answer 1

如果你从主线程开始连接,是的,这是正确的.我只是使用GCD在主线程上创建并启动连接,以避免考虑运行循环.

dispatch_async(dispatch_get_main_queue(), ^{
    NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
    [conn start];
});

从任何地方工作,您不必跟踪运行循环或线程.