iPhone:使用 NSStream 捕获连接错误

Question

我编写了一个程序，使用 Apple 流编程指南中概述的 NSStream 协议(protocol)连接到给定 IP 上的服务器。数据的连接和传输工作完美，但是如果用户指定了错误的 IP 并且程序尝试打开流，则会导致程序无响应。

据我所知，handleEvent 方法检测到流错误，但是当我检查 eventCode == NSStreamEventErrorOccurred 的条件时，似乎没有发生任何事情。我的连接代码如下:

NSString *hostString = ipField.text;

    CFReadStreamRef readStream;

    CFWriteStreamRef writeStream;

    CFStreamCreatePairWithSocketToHost(NULL, (CFStringRef)hostString, 10001, &readStream, &writeStream);



    inputStream = (NSInputStream *)readStream;

    outputStream = (NSOutputStream *)writeStream;

    [inputStream setDelegate:self];

    [outputStream setDelegate:self];

    [inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

    [outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

    [inputStream open];

    [outputStream open];

知道如何在无法建立连接时指定超时值或允许按钮触发流的关闭吗？

Answer 1

Any idea as to how I can specify a timeout value or allow for a button to trigger the closing of the streams if a connection cannot be made?

使用NSTimer。

在你的.h中:

...
@interface MyViewController : UIViewController
{
    ...
    NSTimer* connectionTimeoutTimer;
    ...
}
...

在你的.m中:

...
@interface MyViewController ()
@property (nonatomic, retain) NSTimer* connectionTimeoutTimer;
@end

@implementation MyViewController

...
@synthesize connectionTimeoutTimer;
...

- (void)dealloc
{
    [self stopConnectionTimeoutTimer];
    ...
}

// Call this when you initiate the connection
- (void)startConnectionTimeoutTimer
{
    [self stopConnectionTimeoutTimer]; // Or make sure any existing timer is stopped before this method is called

    NSTimeInterval interval = 3.0; // Measured in seconds, is a double

    self.connectionTimeoutTimer = [NSTimer scheduledTimerWithTimeInterval:interval
                                                                   target:self
                                                                 selector:@selector(handleConnectionTimeout:)
                                                                 userInfo:nil
                                                                  repeats:NO];
}

- (void)handleConnectionTimeout
{
    // ... disconnect ...
}

// Call this when you successfully connect
- (void)stopConnectionTimeoutTimer
{
    if (connectionTimeoutTimer)
    {
        [connectionTimeoutTimer invalidate];
        [connectionTimeoutTimer release];
        connectionTimeoutTimer = nil;
    }
}