Question

我是应用程序开发的新手，已经创建了一个使用uiwebviews的几个viewcontrollers的应用程序。我想在iphone未连接到互联网时添加警报视图。我尝试过实现不同的代码，但是不会弹出alertview。

继承我的代码。

//
//  ViewControllersocialgo.h
//  GO!SocialMedia
//
//  Created by Adam Rais on 28/11/2012.
//  Copyright (c) 2012 SocialGO. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "Reachability.h"

@interface ViewControllersocialgo : UIViewController <UIWebViewDelegate>
@property (strong, nonatomic) IBOutlet UIWebView *socialgo;

@end

和ViewControllerpractical.m

//
//  ViewControllerpractical.m
//  GO!SocialMedia
//
//  Created by Adam Rais on 28/11/2012.
//  Copyright (c) 2012 SocialGO. All rights reserved.
//

#import "ViewControllersocialgo.h"
#import <sys/socket.h>
#import <netinet/in.h>
#import <SystemConfiguration/SystemConfiguration.h>





@interface ViewControllersocialgo ()

@end

@implementation ViewControllersocialgo


-(BOOL) isInternetAvailable {
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    SCNetworkReachabilityRef reachability =        SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct     sockaddr*)&zeroAddress);
if(reachability != NULL) {
    //NetworkStatus retVal = NotReachable;
    SCNetworkReachabilityFlags flags;
    if (SCNetworkReachabilityGetFlags(reachability, &flags)) {
        if ((flags & kSCNetworkReachabilityFlagsReachable) == 0)
        {
            // if target host is not reachable
            return NO;
        }

        if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0)
        {
            // if target host is reachable and no connection is required
            //  then we'll assume (for now) that your on Wi-Fi
            return YES;
        }


        if ((((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) ||
             (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0))
        {
            // ... and the connection is on-demand (or on-traffic) if the
            //     calling application is using the CFSocketStream or higher APIs

            if ((flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0)
            {
                // ... and no [user] intervention is needed
                return YES;
            }
        }

        if ((flags & kSCNetworkReachabilityFlagsIsWWAN) ==     kSCNetworkReachabilityFlagsIsWWAN)
        {
            // ... but WWAN connections are OK if the calling application
            //     is using the CFNetwork (CFSocketStream?) APIs.
            return YES;
        }
    }
}

return NO;

}




- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
    // Custom initialization
}
return self;
}

- (void)viewDidLoad
{
[super viewDidLoad];
[_socialgo setDelegate:self];
NSString *fullURL=@"http://adam182testing.comoj.com/socialgo.html";
NSURL *url=[NSURL URLWithString:fullURL];
NSURLRequest *requestOBJ=[NSURLRequest requestWithURL:url];
[_socialgo loadRequest:requestOBJ];
}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end

由于

Answer 1

不要等待错误告诉用户他没有互联网连接。使用Apple自己的方法来检测使用ARC的连接 - Apple sample project或this version。如果用户失去连接，它会立即告诉您。

Answer 2

您的视图控制器必须实现UIWebViewDelegate，请尝试此代码

ViewControllerpractical.h

//
//  ViewControllerpractical.h
//  GO!SocialMedia
//
//  Created by Adam Rais on 28/11/2012.
//  Copyright (c) 2012 SocialGO. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface ViewControllerpractical : UIViewController <UIWebViewDelegate>
@property (strong, nonatomic) IBOutlet UIWebView *practical;

@end

ViewControllerpractical.m

//
//  ViewControllerpractical.m
//  GO!SocialMedia
//
//  Created by Adam Rais on 28/11/2012.
//  Copyright (c) 2012 SocialGO. All rights reserved.
//

#import "ViewControllerpractical.h"

@interface ViewControllerpractical ()

@end

@implementation ViewControllerpractical

- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
                                                message:@"Can't connect. Please check your internet Connection"
                                               delegate:self
                                      cancelButtonTitle:@"OK"
                                      otherButtonTitles:nil];
[alert show];
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
    // Custom initialization
}
return self;
}

- (void)viewDidLoad
{
[super viewDidLoad];
[_practical setDelegate:self];
NSString *fullURL=@"http://adam182testing.comoj.com/practical.html";
NSURL *url=[NSURL URLWithString:fullURL];
NSURLRequest *requestOBJ=[NSURLRequest requestWithURL:url];
[_practical loadRequest:requestOBJ];
}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end

无论如何，正如Eli Ganem所说，使用可达性更好。

我在我的项目中使用此功能：

-(BOOL) isInternetAvailable {
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr*)&zeroAddress);
    if(reachability != NULL) {
        //NetworkStatus retVal = NotReachable;
        SCNetworkReachabilityFlags flags;
        if (SCNetworkReachabilityGetFlags(reachability, &flags)) {
            if ((flags & kSCNetworkReachabilityFlagsReachable) == 0)
            {
                // if target host is not reachable
                return NO;
            }

            if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0)
            {
                // if target host is reachable and no connection is required
                //  then we'll assume (for now) that your on Wi-Fi
                return YES;
            }


            if ((((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) ||
                 (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0))
            {
                // ... and the connection is on-demand (or on-traffic) if the
                //     calling application is using the CFSocketStream or higher APIs

                if ((flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0)
                {
                    // ... and no [user] intervention is needed
                    return YES;
                }
            }

            if ((flags & kSCNetworkReachabilityFlagsIsWWAN) == kSCNetworkReachabilityFlagsIsWWAN)
            {
                // ... but WWAN connections are OK if the calling application
                //     is using the CFNetwork (CFSocketStream?) APIs.
                return YES;
            }
        }
    }

    return NO;

}

没有互联网连接xcode警报视图

2 个答案: