试图让networking错误警报显示在iPhone应用程序？
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 这里是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; 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
该应用程序运行良好，没有任何错误或警告，但它没有显示警报，当没有互联网连接。 有没有人有任何想法，为什么这是？
你实际上并没有在任何地方显示警报。 要做到这一点，你会做类似于以下的事情：
UIAlertView *errorView = [[UIAlertView alloc] initWithTitle:@"Internet Unavailable" message:@"MESSAGE ABOUT INTERNET UNAVAILABLE HERE." delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil]; [errorView show]; [errorView release];
此外，重要的是要注意，viewDidLoad可以在初始化后在视图控制器上调用任意次数。 最好在指定的初始化器中声明任何通知观察者。