试图在我的应用程序中实现networking错误警报？
好的，我试图让这个应用程序显示networking错误警报代码。 我添加了SystemConfiguration.framework框架和Apple的“Reachability”示例代码。
这里是viewcontroller.h文件：
#import <UIKit/UIKit.h> @class Reachability; @interface Test_Internet_ConnectionViewController : UIViewController { Reachability* internetReachable; Reachability* hostReachable; } @property BOOL internetActive; @property BOOL hostActive; - (void) checkNetworkStatus:(NSNotification *)notice; @end 这是viewcontroller.m文件：
#import "Test_Internet_ConnectionViewController.h" #import "Reachability.h"; @implementation Test_Internet_ConnectionViewController @synthesize internetActive; @synthesize hostActive; /* // The designated initializer. Override to perform setup that is required before the view is loaded. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; if (self) { // Custom initialization } return self; } */ /* // Implement loadView to create a view hierarchy programmatically, without using a nib. - (void)loadView { } */ // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; // check for internet connection [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkNetworkStatus:) name:kReachabilityChangedNotification object:nil]; internetReachable = [[Reachability reachabilityForInternetConnection] retain]; [internetReachable startNotifier]; // check if a pathway to a random host exists hostReachable = [[Reachability reachabilityWithHostName: @"www.apple.com"] retain]; [hostReachable startNotifier]; // now patiently wait for the notification } /* // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } */ - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { // Release any retained subviews of the main view. // eg self.myOutlet = nil; } - (void) checkNetworkStatus:(NSNotification *)notice { // called after network status changes NetworkStatus internetStatus = [internetReachable currentReachabilityStatus]; switch (internetStatus) { case NotReachable: { NSLog(@"The internet is down."); self.internetActive = NO; UIAlertView *errorView = [[UIAlertView alloc] initWithTitle:@"Internet Unavailable" message:@"This page cannot load, please check your internet connection and try again." delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil]; [errorView show]; [errorView release]; break; } case ReachableViaWiFi: { NSLog(@"The internet is working via WIFI."); self.internetActive = YES; break; } case ReachableViaWWAN: { NSLog(@"The internet is working via WWAN."); self.internetActive = YES; break; } } NetworkStatus hostStatus = [hostReachable currentReachabilityStatus]; switch (hostStatus) { case NotReachable: { NSLog(@"A gateway to the host server is down."); self.hostActive = NO; break; } case ReachableViaWiFi: { NSLog(@"A gateway to the host server is working via WIFI."); self.hostActive = YES; break; } case ReachableViaWWAN: { NSLog(@"A gateway to the host server is working via WWAN."); self.hostActive = YES; break; } } } - (void)dealloc { [super dealloc]; [[NSNotificationCenter defaultCenter] removeObserver:self]; } @end
如果打开应用程序时没有互联网，错误就会如预期那样工作，但是如果应用程序在通过互联网连接最初打开之后失去连接，错误将显示3次，当然我只想显示一次。
任何人都可以帮我吗？ 提前致谢。
错误查看委托应该可能是自我而不是零，但我不知道这是否会解决问题。 如果没有，问题可能是NSNotificationCenter发送太多的通知给它的观察者（在这个例子中是checkNetworkStatus 。最简单的（但可能不太优雅的）解决scheme是保留一个通知计数器variables，当错误视图显示错误，如果计数器为零，则只显示错误视图。更好的解决scheme是检查传入的通知，并对不同的通知作出不同的响应（或根本不响应）。