objective-c – Xcode和WebView：如果没有互联网连接,则加载本地

目前我正在使用UIWebView为iOS编写应用程序.我的目标是使用WebView显示一个php站点(来自我的web服务器).我对HTMl,CSS,JS和 PHP非常好,但是对象C不是我的优势.但是我设法实现了一切,我的目标是(当iOS没有互联网连接时)在错误警报后显示本地文件而不是服务器上的文件.使用谷歌后,我设法独立完成,但不是作为后备.

现在它显示警报,但点击确定后,用户获得一个空白页面.不是非常用户友好:(在本地html文件中我可以实现一种“刷新按钮”.如果你有一个(更好的？)解决方案,我会很高兴.谢谢！

我的系统：OS X 10.8.2上的Xcode 4.5.1

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController <UIWebViewDelegate>
@property (strong,nonatomic) IBOutlet UIWebView *webView;
@property (weak,nonatomic) IBOutlet UIActivityIndicatorView *loadingSign;
- (void)loadSite;

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController
@synthesize webView;
@synthesize loadingSign;

-(void) webViewDidStartLoad:(UIWebView *)webView {
    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
    [self.loadingSign startAnimating];
    self.loadingSign.hidden = NO;
}

-(void) webViewDidFinishLoad:(UIWebView *)webView {
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
    [self.loadingSign stopAnimating];
    self.loadingSign.hidden = YES;
}

-(void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error {
    [self.loadingSign stopAnimating];
    self.loadingSign.hidden = YES;
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Keine Internetverbindung" message:@"Bitte verbinde dich mit dem Internet." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
}

- (void)loadSite
{
    NSString *fullURL = @"http://website.com";
    NSURL *url = [NSURL URLWithString:fullURL];
    NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
    [webView loadRequest:requestObj];
    webView.scrollView.bounces = NO;
    webView.delegate = self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view,typically from a nib.
    [self loadSite];
}

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

@end

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex

@interface ViewController : UIViewController <UIWebViewDelegate,UIAlertViewDelegate>

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Keine Internetverbindung" message:@"Bitte verbinde dich mit dem Internet." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];