ios版本更新提示

// 提示用户更新
-(void)checkAppUpdate
{
    NSDictionary *infoDict = [[NSBundle mainBundle] infoDictionary];
    
    NSString *nowVersion = [infoDict objectForKey:@"CFBundleVersion"];
    NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://itunes.apple.com/lookup?id=%@", kStoreAppId]];
    NSString * file =  [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:nil];
    
    NSRange substr = [file rangeOfString:@"\"version\":\""];
    NSRange range1 = NSMakeRange(substr.location+substr.length,10);
    NSRange substr2 =[file rangeOfString:@"\"" options:nil range:range1];
    NSRange range2 = NSMakeRange(substr.location+substr.length, substr2.location-substr.location-substr.length);
    NSString *newVersion =[file substringWithRange:range2];
    if(![nowVersion isEqualToString:newVersion])
    {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示" message:@"版本有更新"delegate:self cancelButtonTitle:@"忽略"otherButtonTitles:@"更新",nil];
        [alert show];
    }
}

- (void)alertView:(UIAlertView*)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if(buttonIndex==1)
    {
        // 此处加入应用在app store的地址，方便用户去更新，一种实现方式如下：
        
        NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"https://itunes.apple.com/us/app/che-yi/id1087016587?l=zh&ls=1&mt=8"]];
        [[UIApplication sharedApplication] openURL:url];
    }
}