Best 'init' method to set variable value for iOS 7? - ios

Question

I'm still fairly new to Objective C so please bear with me:
My app has a Delegate, a Navigation Controller, and a View.
I also use a Singleton for "global" variables.
I know I can do this but it seems ungainly:
#import "GlobalData.h"
#synthesize ...
NSInteger junk;
NSInteger moreJunk;
-(void)myMethod{
GlobalData *globDat=[GlobalData getSingleton];
junk=globDat.someValue;
}
-(void)myOtherMethod{
GlobalData *globDat=[GlobalData getSingleton];
moreJunk=globDat.someOtherValue;
}
I'd like to this but it can't:
#import "GlobalData.h"
#synthesize ...
NSInteger junk;
NSInteger moreJunk;
GlobalData *globDat=[GlobalData getSingleton]; //Compiler won't allow this line
-(void)myMethod{
junk=globDat.someValue;
}
-(void)myOtherMethod{
moreJunk=globDat.someOtherValue;
}
However I can do this:
#import "GlobalData.h"
#synthesize ...
NSInteger junk;
NSInteger moreJunk;
GlobalData *globDat;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
globDat=[GlobalData getSingleton];
}
return self;
}
-(void)myMethod{
junk=globDat.someValue;
}
-(void)myOtherMethod{
moreJunk=globDat.someOtherValue;
}
So, is there a standard/common/proper "init" method to use for all Classes?
Should I just do this in every Class?
-(id)init{
if(self=[super init]){
globDat=[GlobalData getSingleton];
}
return self;
}

Answer 1

I know I can do this but it seems ungainly...
You seem to be asking how to do away with the part where you retrieve the value you want from your singleton. The best way to do that is to eliminate the singleton in the first place.
You say that you have an app delegate, a navigation controller, and a view. You probably also have a view controller. If those are the main objects in your application, you might consider storing your data in your view controller. Or, convert your singleton into a legitimate data model, and let your view controller keep a reference to it in a property. Then you can say something like:
-(void)myMethod{
junk = self.model.someValue;
}
which is pretty close to what you seem to be asking for.

Answer 2

It depends on how much you will use GlobalData.
extensive use in many methods
If you plan to make an extensive use of GlobalData in your class (in many methods), then, you should better add
#propertu (nonatomic, readwrite, weak)GlobalData *globalData in your .h
(or, better, in the class extension). In your main init... method, you set the value self.globalData = [GlobalData getSingleton];. You can also do as you did, with an instance variable, GlobalData* myGlobalData in your .h or in the class extension.
Make sure your init... method starts with init and make sure there is a "main" init... method (we call it the "designated initializer"). You can simply override the init method of NSObject. But, if you need, you can define
- (id)initWithString:(NSString*)str
{
self = [super init] ; // or another one ; here you should use the designated init. of the parent class
if (self){
self.string = str ;
self.globalData = [GlobalData getSingleton] ;
}
return self;
}
extensive use in few methods
If you intensively use GlobalData in one or two methods, you don't need to do so. You will just define a local variable GlobalData * globalData = [GlobalData getSingleton]; and use it.
The third code you propose is not objected-oriented.

Answer 3

I'm not 100% sure what you're question is really about (singletons as a common pattern vs common -init method?), but it is common to create what is called a designated initializer for your class. If you're not using a singleton pattern an init method signature that takes a value might look like this:
-(id)initWithValue:(NSString*)newValue;
As for using a singleton pattern to provide access to your variables I would recommend a more loosely coupled approach, especially if the number of values your singleton class manages begins to grow. I would put those variables into their own classes (separated logically) and use them as needed, by passing them to constructors, or instantiating them. That's an opinion/philosophy issue, though.

Answer 4

I ended up using this to resolve the question.
(Again I was primarily trying to clean out the redundancy of code)
In my Class modules I did the following:
#import "GlobalData.h"
GloablData *globDat;
-(id)init{
if(self=[super init]){
globDat=[GlobalData getSingleton];
}
return self;
}
...
-(void)someMethod{
int junk=globDat.junkvalue;
}