NSURLConnection是否需要NSRunLoop才能执行? [英] NSURLConnection needs a NSRunLoop to execute?

问题描述

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.似乎需要运行循环才能执行.我虽然只执行一次就可以完成.似乎我不需要使运行循环运行，除了在每次调用connect时一次获取此URL之外.有更好的方法吗?

I'm trying to fetch the contents of a URL from a method called connect. It reads its configuration settings and attempts to fetch the URL. It appears to need the run loop to execute. I though it would just execute once and be done. It seems that I don't need to have that run loop running for any reason other than to fetch this URL once, whenever connect is called. Is there a better way do do this?

- (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);
}

推荐答案

如果要从主线程启动连接，是的，这是正确的.我只是使用GCD在主线程上创建和启动连接，而不必考虑运行循环.

If you're starting the connection off of the main thread, yes, this is correct. I just use GCD to create and start the connection on the main thread to avoid having to think about run loops.

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

可以在任何地方工作，而不必跟踪运行循环或线程.

Works from anywhere and you don't have to keep track of run loops or threads.

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