is a simple trick to open iOS application and even a page within the application from WatchKit

How to open iOS application from WatchKit

/*
//
//  How to open iOS application using WatchKit
//
//  Created by Mokhlas Hussein on 09/04/15.
//  Copyright (c) 2015 iMokhles (Mokhlas Hussein). All rights reserved.
//
*/

/******* Within the App Watch Extension *******/
#import <WatchKit/WatchKit.h>
#import <Foundation/Foundation.h>

@interface InterfaceController : WKInterfaceController
@end

@implementation InterfaceController
- (void)awakeWithContext:(id)context {
    [super awakeWithContext:context];
    // Configure interface objects here.
    
}
- (void)willActivate {
    // This method is called when watch view controller is about to be visible to user
    [super willActivate];
}

- (void)didDeactivate {
    // This method is called when watch view controller is no longer visible
    [super didDeactivate];
}
- (IBAction)openAboutUS {
    NSDictionary *requst = @{@"pageID":@"openAboutUS"};
    [InterfaceController openParentApplication:requst reply:^(NSDictionary *replyInfo, NSError *error) {
        // u can get any reply here or check if there are an error
    }];
}
@end

/******* Within the App Delegate *******/
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (strong, nonatomic) UIWindow *window;
@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
	// checking the launch url
    if (![launchOptions objectForKey:UIApplicationLaunchOptionsURLKey]) {
        NSLog(@"url is nil");
    } else {
        NSLog(@"url is not nil");
    }
    return YES;
}

- (void)application:(UIApplication *)application handleWatchKitExtensionRequest:(NSDictionary *)userInfo reply:(void (^)(NSDictionary *))reply {
    // handle the request from the watch
    NSString *urlStrin;
    urlStrin = [userInfo objectForKey:@"pageID"];
	[[UIApplication sharedApplication] openURL:[NSURL URLWithString:[NSString stringWithFormat:@"URL-SCHEME://%@", urlStrin]]];

}

- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url {
    // handle the request from the url scheme ;)
    NSString *pageName = [[NSString stringWithFormat:@"%@", url.host] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    if ([pageName isEqualToString:@"openAboutUS"]) {
        [[NSNotificationCenter defaultCenter]postNotificationName:@"OpenAboutUsNotification" object:nil];
    }
    return YES;
}
@end

/******* Within the Main ViewController *******/
@interface MainViewController : UIViewController
@end

@implementation MainViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    // add notification to open the requested page
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(aboutPresd:) name:@"OpenAboutUsNotification" object:nil];
}
- (void)aboutPresd:(id)sender {
	// i used to push it from the storyboard u can use any other method
    UIViewController *aboutPage = [self.storyboard instantiateViewControllerWithIdentifier:@"aboutPageID"];
    [self.navigationController pushViewController:aboutPage animated:YES];
}
@end
//