ios Pass an object between more than 2 view controllers - ios

Question

I have my classe which contains my data Data
I created my object in my first View called ViewController
I will create others viewControllers and I want to read and write datas in the object "man1" created in my ViewController.
How can I do that ?
Thank you very much.
This is my code so far:
Data.H
#import <Foundation/Foundation.h>
#interface Data : NSObject
{
NSString *name;
int age;
NSString *city;
}
- (id)initWithName:(NSString *)aName ;
- (NSString*) name;
- (int) age;
- (NSString*) city;
//- (void) setPrenom:(NSString*) prenom;
- (void) setName:(NSString*) newName;
- (void) setAge:(int) newAge;
- (void) setCity:(NSString*) newCity;
#end
Data.m
#import "Data.h"
#implementation Data
- (id)initWithName:(NSString *)aName
{
if ((self = [super init]))
{
self.name = aName;
}
return self;
}
//getter
- (NSString*) name
{
return name;
}
- (int) age{
return age;
}
- (NSString*) city{
return city;
}
//setter
- (void) setName:(NSString*)newName
{
name = newName;
}
- (void) setAge:(int) newAge
{
age = newAge;
}
- (void) setCity:(NSString *)newCity
{
city = newCity;
}
#end
ViewController.h
#import <UIKit/UIKit.h>
#import "Data.h"
#interface ViewController : UIViewController
{
int testint;
}
#property (readwrite) Data *man1;
#property (weak, nonatomic) IBOutlet UILabel *labelAff;
#end
ViewController.m
#import "ViewController.h"
#import "Data.h"
#interface ViewController ()
#end
#implementation ViewController
#synthesize man1 = _man1;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSString * name1 = #"Bob";
_man1 = [[Data alloc]initWithName:name1 ];
NSLog(#" %# ", _man1.name);
[_man1 setAge:29];
NSLog(#" %d ", _man1.age);
[_man1 setCity:#"Tapei"];
_labelAff.text = [_man1 city];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end

Answer 1

Your approach is not going to work, because you allocate a new instance of Data each time a view is loaded, and because each view controller gets its own Data object.
One approach to fixing this is making your Data class a singleton. Your view controllers will be accessing a single instance of Data, ensuring that the information is shared among the view controllers:
Data.h
#interface Data : NSObject
{
NSString *name;
int age;
NSString *city;
}
- (id)initWithName:(NSString *)aName ;
- (NSString*) name;
- (int) age;
- (NSString*) city;
- (void) setName:(NSString*) newName;
- (void) setAge:(int) newAge;
- (void) setCity:(NSString*) newCity;
+(Data*)instance;
#end
Data.m
#implementation Data
-(id)initWithName:(NSString *)aName {
if(self=[super init]) {
...
}
return self;
}
+(Data*)instance {
static dispatch_once_t once;
static Data *sharedInstance;
dispatch_once(&once, ^{
sharedInstance = [[self alloc] initWithName: ...];
});
return sharedInstance;
}
#end