how to change WebView with buttons in separate View Controller - iphone

Question

I need to change the URL of a WebView (located in WebViewViewController) using buttons in View Controller 1 (called PracticeViewController). I totally understand how to change the web View when it is in the same View Controller as the buttons, but I don't understand how to get the buttons to affect the WebView when the WebView is in a different ViewController than the buttons. Below is the code I currently have:
PracticeViewController.h
#import <UIKit/UIKit.h>
#interface PracticeViewController : UIViewController
- (IBAction)passGoogleButton:(id)sender;
- (IBAction)passYahooButton:(id)sender;
- (IBAction)passBingButton:(id)sender;
/* ok I tried to make this as clear as possible, and you can look at the other files if you don't understand what I mean, but at its core I want to change the web site loaded by the Web View by clicking on the buttons in the other View Controller */
#end
space (BTW is there an easier way to post on StackOverFlow Besides pressing space 4 times for every line of code? am I missing something?)
PracticeViewController.m
#import "PracticeViewController.h"
#import "WebViewViewController.h"
#interface PracticeViewController ()
#end
#implementation PracticeViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)passGoogleButton:(id)sender {
WebViewViewController.webSiteURL = #"http://www.google.com";
/* This supposedly works on a tutorial I saw, but Xcode flags it with the error 'Property webSiteURL not found on object of type 'WebViewViewController'' */
}
- (IBAction)passYahooButton:(id)sender {
WebViewViewController.webSiteURL = #"http://www.yahoo.com";
//same error as above
}
- (IBAction)passBingButton:(id)sender {
WebViewViewController.webSiteURL = #"http://www.bing.com";
//same error as above
}
#end
space
WebViewViewController.h
#import <UIKit/UIKit.h>
#interface WebViewViewController : UIViewController
{
UIWebView *myWebView;
NSString *webSiteURL;
}
#property (weak, nonatomic) IBOutlet UIWebView *myWebView;
#property (strong, nonatomic) NSString *webSiteURL;
/* I don't entirely understand what 'strong' means but I know it has to do with memory retention and that it (supposedly) should be used when I wan to transfer the value of the string 'webSiteURL' to the other ViewController */
#end
space
WebViewViewController.m
#import "WebViewViewController.h"
#interface WebViewViewController ()
#end
#implementation WebViewViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
[myWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:webSiteURL]]];
/* As you can see above, the WebView loads from the string 'webSiteURL' but I can't figure out how to assign different values to it based on what button is clicked in the other View Controller so that it will run in ' - (void)viewDidLoad.' I already know how to transfer the value of the string to other things within another view controller (like into a label or a text field) but what I really need to know is how to get the string 'webSiteURL' to change before the view is loaded */
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end

Answer 1

You have the right idea but you are missing a step here. You are never creating an instance of webViewController.
What you need somewhere is...
webViewcontroller *MyWebController = [[webViewController alloc] init];
It depends on how you are presenting the WebViewController. If you simply want the button to pop up the WebViewController modally you could use the following:
- (IBAction)passGoogleButton:(id)sender {
webViewController *myWebVC = [[webViewController alloc] init];
[myWebVC setWebSiteURL:#"http://www.google.com"];
[self presentViewController:myWebVC animated:YES completion:nil];
}
So, you can see here. You create the instance of the webViewController called myWebVC. Then you pass the string to it. So when myWebVC loads and it hits viewDidLoad, it will use the string that you passed in already and load the web view with that content. Hope that helps.
Also, Make sure you #synthesize your properties in your .m files.

Answer 2

You can use nsnotificationcenter to accomplish this task.
First register to notificationcenter in WebViewController, then send notification from another controller.
Here's a sample for registering to notificationcenter in WebViewController
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(nMessageOpenURL:) name:#"nMessageOpenURL" object:nil];
This is the code to run the logic when you receive the notification. (in WebViewController)
- (void)nMessageOpenURL:(NSNotification *)note {
//run the logic in here.
}
And finally this is the code where you trigger the notification.
[[NSNotificationCenter defaultCenter] postNotificationName:#"nMessageOpenURL" object:nil];
Here's the Apple documentation.

Answer 3

I got to know that you are trying to pass the value of the string of url between two view controllers but you are not getting it right!!
So if you are using storyboard you can try out passing this value using Segue. For Eg: you can use prepareForSegue to set the different values using if-else construct.
And if you are not using segue the best practice to pass those values will be using delegate.
Just create a delegate method and pass the url string as an argument.
Hope this works :)