Question

我使用以下方法检查我的应用是否有连接。它很简单，适合我的需求。

+ (void)checkInternet:(connection)block
{
    NSURL *url = [NSURL URLWithString:@"http://www.google.com/"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    request.HTTPMethod = @"HEAD";
    request.cachePolicy = NSURLRequestReloadIgnoringLocalAndRemoteCacheData;
    request.timeoutInterval = 10.0;

    [NSURLConnection sendAsynchronousRequest:request
                                       queue:[NSOperationQueue mainQueue]
                           completionHandler:
     ^(NSURLResponse *response, NSData *data, NSError *connectionError)
     {
         block([(NSHTTPURLResponse *)response statusCode] == 200);
     }];
}

然而，我想要做的是，如果状态没有返回200，我想再次检查，至少几次。以1秒为间隔进行此操作的最佳方式是什么？

以下是我如何调用上述方法。

 [self checkInternet:^(BOOL internet)
    {
         if (internet)
         {
             // "Internet" aka Google
         }
         else
         {
             // No "Internet" aka no Google
         }
    }];

Answer 1

我使用Reachability来检测常规网络连接问题（请参阅答案结束）。我使用以下方法执行重试。

- (void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay;

你可以调整你的系统，使其具有一个新的类方法，该方法具有可选的重试次数。

NB。未测试以下内容。它只是为了给你一般的想法。

// Variable to track number of retries left. If you had a shared instance
// a property would be easier.
static NSUInteger maxConnectionTries = 0;

// New method which lets you pass a retry count.
+ (void)checkInternet:(connection)block withMaxTries:(NSUInteger)maxTries
{
   maxConnectionTries=maxTries;
   [self checkInternet:block];
}

// Your original code extended to retry by calling itself when code 200
// is seen on a delay of 1s. Defaults to old code when retry limit exceeded
// or non 200 code received.
+ (void)checkInternet:(connection)block
{
    NSURL *url = [NSURL URLWithString:@"http://www.google.com/"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    request.HTTPMethod = @"HEAD";
    request.cachePolicy = NSURLRequestReloadIgnoringLocalAndRemoteCacheData;
    request.timeoutInterval = 10.0;

    [NSURLConnection sendAsynchronousRequest:request
                                       queue:[NSOperationQueue mainQueue]
                           completionHandler:
     ^(NSURLResponse *response, NSData *data, NSError *connectionError)
     {
         if ([(NSHTTPURLResponse *)response statusCode] != 200 &&
             maxConnectionRetries > 0){
           maxConnectionRetries--;
           [self performSelector:@selector(checkInternet:) withObject:block afterDelay:1.0]; 
         }
         else{
           maxConnectionRetries = 0;
           block([(NSHTTPURLResponse *)response statusCode] == 200);
         }
     }];
}

对于互联网连接的一般检测，最好使用可达性。请参阅here。

我从AppDelegate代码启动可访问性处理程序，然后在发生连接更改时发布本地通知。这允许应用程序始终在viewWillAppear和viewWillDisappear内接收连接更改通知和瞬态视图控制器，以便在他们对连接更改感兴趣时注册和取消注册本地通知。

Answer 2

这是我提出的：

+ (void)checkInternet:(connection)block withMaxTries:(NSUInteger)maxTries
{
    NSURL *url = [NSURL URLWithString:@"http://www.google.com/"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    request.HTTPMethod = @"HEAD";
    request.cachePolicy = NSURLRequestReloadIgnoringLocalAndRemoteCacheData;
    request.timeoutInterval = 10.0;

    [NSURLConnection sendAsynchronousRequest:request
                                       queue:[NSOperationQueue mainQueue]
                           completionHandler:
     ^(NSURLResponse *response, NSData *data, NSError *connectionError)
     {
         if ([(NSHTTPURLResponse *)response statusCode] != 200 &&
             maxTries > 0){

             dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 1 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{

                 [self checkInternet:block withMaxTries:maxTries - 1];
             });
        }
         else{
             block([(NSHTTPURLResponse *)response statusCode] == 200);
         }
     }];
}

的NSTimer？ - 检查连接iOS

2 个答案: