Xcode - I can't run the whole methods from AppDelegate - objective-c

Question

I'm using custom URL schemes to open my app, then get the link and run in a method. But I can't really run the method.
For example, I can't load web views or change labels or text fields. So how do I load web views and change labels?
AppDelegate.m:
- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url {
if (!url) { return NO; }
NSString *URLopen= [[url host] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
ViewController *vc = [[ViewController alloc]init];
vc.URLschemeLink = URLopen;
[vc URLscheme];
return YES;
}
ViewController.h:
#interface ViewController : UIViewController<MFMailComposeViewControllerDelegate> {
NSString *URLschemeLink;
}
-(void)URLscheme;
#end
ViewController.m:
#implementation ViewController
#synthesize URLschemeLink;
-(void)URLscheme {
//for example:
label.text = #"Hello"; //nothing will happen
[webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:#"http://www.google.com"]]]; //Nothing will happen
NSLog ("Method Works Perfect"); //will happen
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:#"Title:"
message:[NSString stringWithFormat:#"%#", URLSchemeLink]
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[alert show];
//UIAlertView will work perfectly and show the URLschemeLink from AppDelegate.
}
ok How to load the label/webview anyway?
i tested to pass a bool named runURLscheme (=true) from app delegate.
then i wrote in ViewDidLoad:
if(runURLscheme==true) {
[self URLScheme];
}
but this will not work, it will not run the URLscheme method.
How can i load the labels/webviews anyway?

Answer 1

The main views associated with view controllers are generally lazy loaded. Just because the view controller is initialised, it doesn't mean it's loaded its main view yet. Your views are only safe to access once viewDidLoad has been called.
Generally speaking, this pattern works well:
Store your data independently of any views that display it.
When your custom URL scheme runs, update this data.
Have a method on your view controller that updates its views from this data.
Call this method from viewDidLoad.
If there's a chance this data will be updated after your views have already been loaded (e.g. if you are receiving data from the network), then use notifications or KVO to call your view updating method again.