Question

In Settings.bundle, I have a text input with the identifier url_preference.

Using ViewController.h, ViewController.m, and my storyboards I have a UIWebView set up that displays a url from the Settings:

- (void) updateBrowser {   
    NSString *fullURL = [[NSUserDefaults standardUserDefaults] stringForKey:@"url_preference"];
    NSURL *url = [NSURL URLWithString:fullURL];
    NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
    [_EmbeddedBrowser loadRequest:requestObj];    
}

This works.

When the URL in the Settings is changed, however, the UIWebView does not update to reflect the new URL.

By disallowing the app to run in the background, the problem of not reflecting updated URLs is solved. However, a new problem arises: sessions are not preserved if the URL in Settings is left unchanged. UIWebView should only update if the url_preference is changed.

I’ve been attempting to use applicationWillEnterForeground in AppDelegate.m to force the UIWebView to reload, however I’m having trouble.

In the ViewController, I can run:

- (void)viewDidLoad {
     [self updateBrowser];
}

But it doesn’t update when I try to run the same thing in the App Delegate:

- (void)applicationWillEnterForeground:(UIApplication *)application
{

    ViewController *vc = [[ViewController alloc]init];
    [vc updateBrowser];
}

(I also included - (void) updateBrowser; in ViewController.h, and #import "ViewController.h" in AppDelegate.m

Thank you.

Answer 1

- (void)viewDidLoad
{
    [self updateBrowser];
    [super viewDidLoad];
    NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
    [center addObserver:self
               selector:@selector(defaultsChanged:)
                   name:NSUserDefaultsDidChangeNotification
                 object:nil];
}

- (void)defaultsChanged:(NSNotification *)notification {
    [self updateBrowser];
}

- (void) updateBrowser {

    NSString *fullURL = [[NSUserDefaults standardUserDefaults] stringForKey:@"url_preference"];
    NSURL *url = [NSURL URLWithString:fullURL];
    NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
    [_EmbeddedBrowser loadRequest:requestObj];

}

Luckily, there is no need to use the AppDelegate for this type of situation. There is actually a notification that you listen for when the Default Settings change. You have to set up the ViewController as an observer and have a function execute every time the NSUserDefaultsDidChangeNotification is sent out. This notification will automatically occur every time the Default Settings for the app are changed in the settings. This way you don’t have to refresh every time the app comes to the foreground, only when the settings change.