iOS: Singleton returning null - ios

Question

I have a singleton and I pass data to it but it returns null can you please help me in my situation. Thanks in advance :)
Here's my code
Card.h
#property (weak,nonatomic) NSString *email;
#property (weak,nonatomic) NSString *fName;
#property (weak,nonatomic) NSString *lName;
#property (weak,nonatomic) NSString *category;
+(Card *)getCard;
Card.m
#synthesize email;
#synthesize fName;
#synthesize lName;
#synthesize category;
static csCard *instance;
+(Card *) getCard
{
#synchronized (self)
{
if(instance == nil)
{
instance = [[Card alloc]init];
}
}
return instance;
}
- (id) init{
self.email = [[NSUserDefaults standardUserDefaults]stringForKey:#"email"];
self.fName = [[NSUserDefaults standardUserDefaults]stringForKey:#"firstName"];
self.lName = [[NSUserDefaults standardUserDefaults]stringForKey:#"lastName"];
self.category = #"TestCategory";
return self;
}
and here's my test code to see if it's working
Test.m
Card *card = [Card getCard];
[card setEmail:self.emailField.text];
NSLog(#"%#",card.email);
but this code give me (null)

Answer 1

Modify your class like this.
Card.h
#property (strong,nonatomic) NSString *email; //Let the modal be strong property
#property (strong,nonatomic) NSString *fName;
#property (strong,nonatomic) NSString *lName;
#property (strong,nonatomic) NSString *category;
+(Card *)getCard;
Card.m
static Card *instance;
+(Card *) getCard
{
#synchronized (self)
{
if(instance == nil)
{
instance = [[Card alloc]init];
}
}
return instance;
}
- (NSString)email{
return [[NSUserDefaults standardUserDefaults]stringForKey:#"email"];
}
- (void)setEmail:(NSString)email{
[[NSUserDefaults standardUserDefaults] setString:email forkey:#"email"];
}
No need of overriding init
in your test class
Card *card = [Card getCard];
[card setEmail:self.emailField.text];
NSLog(#"%#",card.email);

Answer 2

static csCard *instance;
+(csCard *) getCard
{
#synchronized (self)
{
if(instance == nil)
{
instance = [[csCard alloc]init];
}
}
return instance;
}
Replace it with this code
static Card *instance;
+(Card *) getCard
{
#synchronized (self)
{
if(instance == nil)
{
instance = [[Card alloc]init];
}
}
return instance;
}
The Class name Of the instance Object was wrong and In singleton method,the return datatype was also wrong. I think u will understand what I am saying.

Answer 3

+ (Card *)instance {
static Card *sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedInstance = [[Card alloc] init];
});
return sharedInstance;
}
It should be work

Answer 4

With the help of what βhargavḯ sujjested u can modify your code as below because
in the line static csCard *instance; u are using csCard i think it is typo so better u can do like this,
#import "Card.h"
static dispatch_once_t onceDispach;
#implementation Card
#synthesize email = _email;
#synthesize fName;
#synthesize lName;
#synthesize category;
static Card *instance = nil; //change this to Card because this instance which is of type Card
+(Card *)getCard
{
dispatch_once(&onceDispach, ^{
instance = [[self alloc] init];//careate Card shared object named instance
});
return instance;
}
- (id) init
{
self.email = [[NSUserDefaults standardUserDefaults]stringForKey:#"email"];
self.fName = [[NSUserDefaults standardUserDefaults]stringForKey:#"firstName"];
self.lName = [[NSUserDefaults standardUserDefaults]stringForKey:#"lastName"];
self.category = #"TestCategory";
return self;
}
#end
- (NSString *)email
{
return _email;
}
- (void)setEmail:(NSString *)email
{
_email = email;
NSUserDefaults *userDefault = [NSUserDefaults standardUserDefaults];
[userDefault setObject:email forKey:#"email"];
}
in the class where u are using this shared instance use like below
- (void)actionMathodCalled
{
Card *card = [Card getCard];
NSLog(#"before saving to defaults->%#",card.email);
[card setEmail:#"happyCoding#ymail.com"];
NSLog(#"after savng to defaults->%#",card.email);
}