Question

我的应用正在使用网络连接，如下所示：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{ 
    .
    .
    .
    receivedData = [[NSMutableData alloc] init];
}

-(void) dataFromWeb{
request = [[NSURLRequest alloc] initWithURL: url];
theConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self];

if (theConnection) {
    receivedData = [[NSMutableData data] retain];
    NSLog(@"** NSURL request sent !");
} else {

    NSLog(@"Connection failed");
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    .
    .
    .
    [theConnection release];
    [request release];

// Here - using receivedData
[receivedData release];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
      [receivedData setLength:0];
}

- (void)connection:(NSURLConnection *)connection
  didFailWithError:(NSError *)error
{
    [theConnection release];
    [request release];
    [receivedData release];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [receivedData appendData:data];
}

。在应用程序的下方是这个片段（onButtonPressed）：

if (theConnection) {
    // Create the NSMutableData to hold the received data.
    // receivedData is an instance variable declared elsewhere.
    receivedData = [[NSMutableData data] retain];
} else {
    NSLog(@"Connection failed");
}

我想要了解的是：

如果我想创建另一个同时的URLRequest，我是否需要使用不同的连接，以便从网上传来的数据在检索时不会混淆？
在这段代码中，有时代码会在函数 didReceiveResponse（） setLength:0的行上崩溃，当应用程序崩溃时我看到{{1我应该将行更改为
```
receivedData=nil
```
我不太确定这条线在做什么 receivedData = [[NSMutableData data] retain];

Answer 1

我认为处理2个连接的最简单方法是复制NSMutableData。我用这种方式，它对我来说很完美。

在你想要第二次连接时，你要这样做：

receivedData2 = [[NSMutableData alloc] init];

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response  
{  
    if (receivedData2) {
        [receivedData2 setLength:0];  
    }
    else 
    {
        [receivedData setLength:0];  
    }
}  

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data  
{  
    if (receivedData2) {
        [receivedData2 appendData:data];  
    }
    else {    
        [receivedData appendData:data]; 
    }
}

然后，在您请求receiveData2或receivedData

的方法中

当你使用它时别忘了：

receivedData2=nil;
[receivedData2 setLength:0];

Answer 2

您当然需要不同的NSURLConnection。
你可以这样做，但最好找出，为什么它是零，因为它不应该。
它分配一个空的NSMutableData对象。但这对我来说似乎是丑陋的代码，因为你创建了一个自动释放的对象并保留它。最好写[NSMutableData new]或[[NSMutableData alloc] init]。

处理网络连接的正确方法是什么？

2 个答案: