how to check internet connection and stop the application with didFinishLaunchingWithOptions iOS - ios

Question

I'm still learning iOS , just i finish my first application but i want to add some function when the application running , here I'm using did finish launching with option method in appdelegate , i want to change this code , first check if the user have internet or not if not show uialertView also , if there is no internet i need a function can stop the application like
Alert ( this application need internet and you dont have internet right now pls try later ) and the application will exit .
or also in some case maybe the web service out of work
if possible explain me where i should put the if statement and how i can exit the application
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
[[UINavigationBar appearance] setBarTintColor:[UIColor lightGrayColor]];
NSFileManager *fileManger=[NSFileManager defaultManager];
NSError *error;
NSArray *pathsArray = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
NSString *doumentDirectoryPath=[pathsArray objectAtIndex:0];
NSString *destinationPath= [doumentDirectoryPath stringByAppendingPathComponent:#"istudentDatabase.plist"];
// NSLog(#"plist path %#",destinationPath);
//if Plist not exists will copy new one
if ([fileManger fileExistsAtPath:destinationPath]){
NSLog(#"Settings File exists ");
}else{
// Copy New Plist
NSString *sourcePath=[[[NSBundle mainBundle] resourcePath]stringByAppendingPathComponent:#"istudentDatabase.plist"];
[fileManger copyItemAtPath:sourcePath toPath:destinationPath error:&error];
}
settingsClass * settings =[[settingsClass alloc]init];
NSNumber * userid = [settings loadPlist:[NSString stringWithFormat:#"userid"]];
if ([userid intValue] == 0)
{
//NSLog(#"You Dont Have USerid ");
// Send a synchronous request
NSURLRequest * urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://fahads-macbook-pro.local/ios/newuser.php"]];
NSURLResponse * response = nil;
NSError * error = nil;
NSData * data = [NSURLConnection sendSynchronousRequest:urlRequest
returningResponse:&response
error:&error];
if (error == nil)
{
NSDictionary * mydata = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
[settings saveNewUserId:[mydata[#"userid"] intValue]];
NSLog(#"%#",mydata[#"userid"]);
}else{
NSLog(#"Error please Check Your Connections ");
}
}else{
NSLog(#"You Have Userid : %#",userid);
}
NSMutableDictionary * itemsPlist = [[NSMutableDictionary alloc]initWithContentsOfFile:destinationPath];
NSLog(#"Items : %#",itemsPlist);
return YES;
}
also if there is no way to exit the application , i have view controller and on this view controller there is push button i want to hide this button from appdelegate with If statement for example if no connection hide the start button and show some hint there is no connection.
thanks advance