Objective C access variables from other classes? - iphone

Question

I'm trying to get a variable from a class that I made from a table view. Basically what I want this to do is tell the other controller what row was selected so this is what I tried to do.
Table View Class .h file:
#property(nonatomic) NSInteger itemId;
-(NSInteger)itemId;
I would then make methods that set and get the variable in the .m file of the Table View Class
(I synthesized it and did all that stuff, I'm just showing you the methods)
-(NSInteger)itemId {
return self.itemId;
}
And now the table cell selected method...
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)
indexPath {
NSUInteger row = [indexPath row];
self.itemId = row;
//segue stuff (if you want me to include this just let me know)
}
Thats all for that class and now the class that I need the value for
View Controller Class .h that is being pushed via segue
#property (nonatomic) NSInteger itemId;
View Controller Class .m
#import "TableViewController.h"
//Skip a few things
#synthesize itemId;
//skip a few things
-(void)viewDidLoad {
TableViewController *tvc = [[TableViewController alloc] init];
itemId = [tvc itemId];
NSLog(#"%i", itemId);
For some reason this doesn't work... When I print out the "itemId" in the "didselectrow" method it returns the right number but when I try to print it out in the other class it just gives me '0'
Any thoughts?
If there are things that I left out that you want to see in my code I'd be more than happy to write it out :) I just wanted to save time and space by cutting down the code a little.
Thanks in advance!
EDIT:
I did find a possible solution but it involves using the delegate. I'm sure there's got to be a better way of doing this so if you have any ideas, just let me know.

Answer 1

TableViewController *tvc = [[TableViewController alloc] init];
Doing this in a different class you create&initialize a new object, so it will be nill(for int 0). For sharing data between classes&view controllers use Delegates and properties.
With a little code i shall explain;
#import <UIKit/UIKit.h>
//YourClassNameAppDelegate.m
#interface YourClassName : UIResponder <UIApplicationDelegate>
{
NSString *uName;
NSDictionary *YourDictionary;
}
#property (copy, readwrite) NSString *uName;
#property (copy, readwrite) NSString *YourDictionary;
And in the other class you want to use this string and dictionary,
//import your delegate class
#import "YourClassNameAppDelegate"
.
.
.
//to me, do this in viewDidLoad(or something like that) method of new view controller
YourClassNameAppDelegate *sharedData= (YourClassNameAppDelegate *)([[UIApplication sharedApplication]delegate]);
.
.
-(IBAction)sharedData{
NSLog(#"Shared String: %#\n And Shared Dictionary: %#, sharedData.uName, sharedData.YourDictionary);
}

Answer 2

The - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *) is not invoked - you have to select a row to change the value of itemId, and that is not possible between the initialization of the table and the itemId = [tvc itemId]; line.

Answer 3

this code may helps you.
#import <UIKit/UIKit.h>
extern int outsider;
#interface ViewController : UIViewController {
}
#property int outsider;
#end
to all the .m files you #import the .h file where you declared the variable in can acces it.

Answer 4

You are creating a new instance of your table view controller within your detail view controller, this is incorrect and is not going to give you a reference to your original table.
Simply create a property on your pushed view controller which holds whatever detail information you want to pass. Then set this in prepareForSegue: in your table view controller, where segue.destinationViewController will give you a pointer to the VC that is about to appear.
Also, fix your accessor method as suggested by Yuji in comments.

Answer 5

I suggest saving the indexPath for the pressed row in a singleton. Here is a guide on how to use the singleton class to store objects and use them across classes.
In this example you can also just declare an instance variable in the singleton and set it when the row is pressed in the appropriate delegate method for your UITableView. This could be done like so:
#import <Foundation/Foundation.h>
#interface Singleton : NSObject {
NSIndexPath *tableViewPath;
}
#import "DataContainerSingleton.h"
#implementation DataContainerSingleton
#synthesize tableViewPath;
static DataContainerSingleton* _theDataContainerSingleton = nil;
+ (DataContainerSingleton*) theDataContainerSingleton;
{
if (!_theDataContainerSingleton)
_theDataContainerSingleton = [[DataContainerSingleton alloc] init];
return _theDataContainerSingleton;
}
- (id)init
{
self = [super init];
if (self) {
tableViewPath = [NSIndexPath indexPathForRow:0 inSection:0];
}
return self;
}
In your view controller with the UITableView just do like this:
#implementation
- (void)tableView:(UITableView *)tableView
didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
tableViewPath = indexPath;
}
You should adjust your initialization to what would be appropriate for your specific program!

Answer 6

Try this:
#property NSInteger itemId;
Hope this helps you