Initialise Singelton once in class?

Question

I am doing the following in order to initialise my singelton:

ChatDataController *box = [ChatDataController sharedInstance];

The problem is that i use *box in different places, for example in these methods:

- (void) viewDidAppear:(BOOL)animated
- (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

Is there a way to only have to initialise once? so that *box can be used in any method within a given class?

Simple. Make "box" a property, and initialize it in your `init` method. Why make things more complicated than that? — Hot Licks, Aug 01 '13 at 11:33

score 1 · Answer 1 · answered Aug 01 '13 at 11:37

Put this code in your ChatDataController

+ (ChatDataController *)sharedInstance
{
    static ChatDataController *object = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        object = [[ChatDataController alloc] init];
    });
    return object;
}

score 0 · Answer 2 · answered Aug 01 '13 at 22:56

Is there a way to only have to initialise once?

If ChatDataController is a singleton it can only be initialised once.

[ChatDataController sharedInstance] should always return the same instance and only alloc] init] the first time it is called.

If, as you mentioned in one of the comments, you already have your singleton, then simply call [ChatDataController sharedInstance] whenever you need the shared instance. There is no need to store the pointer to the object in a property.

I have given +1 to this answer as I believe it doesn't deserve a -1 as it is correct and informative. — Popeye, Dec 13 '13 at 08:33

score -1 · Answer 3 · answered Aug 01 '13 at 11:29

-1

https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CocoaFundamentals/CocoaObjects/CocoaObjects.html

In "Creating a Singleton Instance"

static MyGizmoClass *sharedGizmoManager = nil;

+ (MyGizmoClass*)sharedManager
{
    if (sharedGizmoManager == nil) {
        sharedGizmoManager = [[super allocWithZone:NULL] init];
    }
    return sharedGizmoManager;
}

answered Aug 01 '13 at 11:29

johnyu

2,152
1
15
33

I already have my Singelton class ready, im wondering how to use `MyGizmoClass` :) – Alosyius Aug 01 '13 at 11:31
You call it like this : yourGizmoClass = [MyGizmoClass sharedManager]; – Larme Aug 01 '13 at 11:42

score -1 · Answer 4 · answered Aug 01 '13 at 13:09

-1

try this one:- create macro in .pch file

first import class

#import"ChatDataController.h"

then create macro (sharedInstance must be class method)

#define box ([ChatDataController sharedInstance])

after that u you can use this object in all classes

answered Aug 01 '13 at 13:09

Chaman Sharma

641
5
10

The chat data controller does not belong in the PCH, and that macro will just make your code look confusing, because `box` will look like a local variable. – Sebastian Aug 01 '13 at 22:53
then pls post best solution if you have any – Chaman Sharma Aug 02 '13 at 05:45

Initialise Singelton once in class?

4 Answers4