Create Array of Location Coordinates Dynamically - ios

Question

I've already made an app that compares the user's location to an array of locations with format...
NSArray *myStationArray;
myStationArray = #[
#{
kStation : #"27200",
kLatitude : #( 41.656467),
kLongitude : #(-81.277963)
},
#{
kStation : #"27650",
kLatitude : #(41.657118),
kLongitude : #(-81.276545)
},
...
Now I want the user to be able to create this array dynamically where they can select an IBAction button that will add their current location (lat long) to a mutable array with the format shown. The kStation value will be inputted by the user. I know conceptual questions are frowned upon so I'll offer these specific questions based on this idea.
1.) Where should I create the mutable array (viewDidLoad, IBAction, didUpdateToLocation, ect.)? It will need to be saved to the app so the user can add and delete from it throughout its life.
2.) What will my IBAction code look like to save the current location and kStation input to create an array to match the example above?
3.) Is this something where you'd want to use a database such as sqlite? I'd prefer to avoid using a database if possible but would like to know the best method of doing this.
Thank you for your time in advance.

Answer 1

You would probably define this NSMutableArray for your list as a class property:
#property (nonatomic, strong) NSMutableArray *stations;
While you're at it, you could define a NSString property for your filename:
#property (nonatomic, strong) NSString *filename;
You could load the previous values or initialize it in viewDidLoad, where kFilename is set to #"stations.plist" or something like that:
NSString *docsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
self.filename = [docsPath stringByAppendingPathComponent:kFilename];
if ([[NSFileManager defaultManager] fileExistsAtPath:self.filename])
self.stations = [NSMutableArray arrayWithContentsOfFile:self.filename];
else
self.stations = [NSMutableArray array];
You could add new values in your IBAction (if you want them to be added when the user clicks on the button) or in didUpdateToLocation (if you want it to be added automatically as the user moves). For example, if you did it in IBAction:
- (IBAction)didTouchUpInsideAddButton:(id)sender
{
NSDictionary *newItem = #{
kStation : ..., // grab your station identifier however you want to do that
kLatitude : #(self.locationManager.location.coordinate.latitude),
kLongitude : #(self.locationManager.location.coordinate.longitude)
};
[self.stations addObject:newItem];
[self.stations writeToFile:self.filename atomically:YES];
}
If your list of stations is likely to get large, then you might want to consider using Core Data or SQLite, but if this list is likely to be reasonably short (i.e. something that you don't mind loading the whole thing into memory at the same time), the above technique of using plists via arrayWithContentsOfFile and writeToFile is probably sufficient.

Answer 2

To answer your questions in order:
1) You would probably want to create and initialize your NSMutableArray in viewDidLoad.
2) You could either create your own class, something similar like MKAnnotation format or create a dictionary and then stick that into an array like so:
-(IBAction)myButtonAction:(id)sender {
NSDictionary *myDictionary = [[NSDictionary alloc] initWithObjectsAndKeys:#"Station", #"27200", #"Latitude", #"41.656467", #"Longitude", #"-81.277963", nil];
[myArray addObject:myDictionary];
}
3) You can load your MutableArray file like this:
NSArray *documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask,
YES);
NSMutableString *documentDirectory = [documentDirectories objectAtIndex:0];
NSString *myPath = [documentDirectory stringByAppendingPathComponent:#"UserData"];
NSMutableArray *myArray = [[NSMutableArray alloc] initWithContentsOfFile:myPath];
You can save your MutableArray file like this:
NSArray *documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSMutableString *documentDirectory = [documentDirectories objectAtIndex:0];
NSString *filePath = [documentDirectory stringByAppendingPathComponent:#"UserData"];
BOOL fileError = [myArray writeToFile:filePath atomically:YES];