Get variable (location information) from other class iOS - ios

Question

in an "OfferViewController.m" I have a locationManager function. In the locationManager function I get the currentLatitude and the currentLongitude. Now in the "OfferDetailViewController.m" I want to send the location via JS to a website.
My problem ist, that in the "OfferDetailViewController.m" I don´t get the location information from the "OfferViewController.m"
Hope somebody can help me... here is my code. Thanks!
OfferViewController.m:
#interface OfferViewController ()
#end
...
#pragma mark -
#pragma mark CLLocationManagerDelegate
-(void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
{
NSString *currentLatitude = [[NSString alloc]
initWithFormat:#"%+.6f",
newLocation.coordinate.latitude];
//NSLog(#"locationManager - latitude: %#", currentLatitude);
NSString *currentLongitude = [[NSString alloc]
initWithFormat:#"%+.6f",
newLocation.coordinate.longitude];
//NSLog(#"locationManager - longitude: %#", currentLongitude);
OfferDetailViewController *offerDetailViewController = [[OfferDetailViewController alloc] init];
offerDetailViewController.longTest = currentLongitude;
offerDetailViewController.latTest = currentLatitude;
}
#end
OfferDetailViewController.m:
#interface OfferDetailViewController ()
#end
...
#synthesize latTest;
#synthesize longTest;
...
- (void)webViewDidFinishLoad:(UIWebView *)offerUrl {
NSLog(#"webViewDidFinishLoad");
if ([[self.offerUrl stringByEvaluatingJavaScriptFromString:#"document.readyState"] isEqualToString:#"complete"]) {
// UIWebView object has fully loaded.
NSLog(#"UIWebView object has fully loaded.");
NSLog(#"webViewDidFinishLoad - longTest: %#", longTest);
NSLog(#"webViewDidFinishLoad - latTest: %#", latTest);
...
}
}

Answer 1

Since you are dealing with two view controllers, it is recommended to use segues. Xcode's storyboard files allow you to use segues visually, with a little programmatic assistance.
Steps
Here are a few steps to accomplishing what is asked in the question. These will be discussed below in the rest of the answer.
Create a segue in storyboard
Name the segue in storyboard
Create a prepareForSegue: method & set the variables in the receiving view controller
Making a segue in storyboard
First, I'd recommend linking the two view controllers via one of these segues. To do this, go to your storyboard and have a look at your starting view controller (in this case, it's OfferViewController). Locate the button or cell (some UI element) that will trigger the transition. Then hit the "control" button on your keyboard and click on that UI element. A blue line should appear. Drag that line across to the view controller that you want to move to (in your case OfferDetailViewController), and release. Then, from the options that are displayed, choose which transition type you prefer (typically, if the view is a detail view, you want to choose "push", but unless you have a UINavigationController setup, this will throw an error. Choose "modal" if you have no idea what I just said there). Your end result should look like this:
Naming a segue in storyboard
Next, you want to name your segue so you can access it programmatically. Go ahead and click on the center icon of the segue. Ihe right side bar in Xcode should flip to a view that looks something like this:
Now, in the Identifier box, type in your segue name. This can be anything you want, but remember what it is because we will use it later. I'd also recommend outlining a general pattern for segue identification, so that if you have many segues, you don't have to keep referencing the storyboard, but for just getting something started, that's not necessary to stress over.
Setting the variables in the receiving view controller
This bit we've got to do programmatically. Apple has a handy function that is defined in UIViewController (thus, can be accessed from any UIViewController). The name if this function is 'prepareForSegue:'. Let's take advantage of that.
# pragma mark - SEGUE PREPARATION
/**
* This method prepares to transition from THIS contoller to another controller that will
* display the data in more detail.
*/
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
/* Verify this is indeed the segue you want; replace "YourSegueName" to whatever you
named your segue. */
if ([[segue identifier] isEqualToString:#"YourSegueName"]) {
OfferDetailViewController *receiverController = (OfferDetailViewController *)[segue destinationViewController];
/* here you can set whatever variables you want in 'receiverController'. These
will be accessible in the viewDidLoad: method. An example is given below. */
[receiverController setWhateverVariable:valueOfWhateverVariable];
}
}
And that's it! The data should be transferred to your new view controller, and you should be good to go!

Answer 2

You can store those double (or strings) values (Lat & Long) in your NSUserDefaults and grab them from your Detail View controller.
The location manager just has to be called before the detail view is shown. Make a key that you can reuse and whenever you re-save your user's new coordinates it will over-write the last ones.
ex.
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
NSString *latitudeKey = #"somelatitudekey";
NSString *longKey = #"..";
[userDefaults setObject:currentLatitude forKey:latitudeKey];
[userDefaults setObject:currentLongitude forKey:longKey];
and to retrieve...
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
NSString *latitudeKey = #"somelatitudekey";
NSString *longKey = #"..";
Double latitudeOnNextView = [userDefaults objectForKey:#"latitudeKey"];
Double longitdeOnNextView = [userDefaults objectForKey:#"longKey"];
Be sure to only store the coordinates (double or string whichever you prefer) into the user defaults - it wont work if you try and save the entire location object that the location manager returns.. unless you serialize it.
Also, when you call for the coordinates in the detail view they very well could be null if the location manager hasn't finished updating the user's location by the time you save them into the user defaults so check for those nils accordingly. **This is most likely the issue you are having now -- when you call your new view controller those values you are passing aren't there yet.