Creating an Instance of Class in IOS 6 [closed] - objective-c

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I have a problem that I hope you can help me with. I have an app with several storyboard views, each with a separate viewcontroller. I want to be able to use my own class in all views in the storyboard. This will make the code in each viewcontroller much cleaner and the whole app easier to debug etc. The class will contain variables and methods.
The overall aim for me is to collect data from the user via buttons and then store these in a database. It will be possible to view and amend data, as well as generating statistics.
As most variables and methods will be used in different views and at different times, I would like to separate all these in separate files.
I can also tell you that this is not a lazy short-cut attempt from me, I have surfed the internet for many, many hours reading hundreds of posts etc and I am still nowhere nearer a solution.
Any input is very much appreciated!
Thank you for taking your time to read this...
SomeClass.h has the following code:
#import <Foundation/Foundation.h>
#interface SomeClass : NSObject
{
NSString *dataOne;
NSString *dataTwo;
NSString *dataThree;
}
- (void) SetDataOne: (NSString*) dataOneReceived;
- (void) SetDataTwo: (NSString*) dataTwoReceived;
- (void) SetDataThree: (NSString*) dataThreeReceived;
- (void) saveSomeData;
#end
SomeClass.m has the following code:
#import "SomeClass.h"
#implementation SomeClass
- (void) SetDataOne: (NSString*) dataOneReceived {
dataOne = dataOneReceived;
}
- (void) SetDataTwo: (NSString*) dataTwoReceived {
dataTwo = dataTwoReceived;
}
- (void) SetDataThree: (NSString*) dataThreeReceived {
dataThree = dataThreeReceived;
}
- (void) saveSomeData {
// Here I do stuff with dataOne etc…
}
#end
SomeView.h has the following code:
#import <UIKit/UIKit.h>
#import "HeadViewController.h"
#import "SomeClass.h"
#interface SomeView : UIViewController
// contains stuff not needed to show here
- (IBAction)Done:(id)sender;
#end
SomeView.m has the following code:
#import "SomeView.h"
#import "SomeClass.h"
#interface SomeView ()
#end
#implementation SomeView
- (void)viewDidLoad
{
[super viewDidLoad];
SomeClass *someClassObject = [[SomeClass alloc] init];
// Do any additional setup after loading the view.
}
// Other standard methods omitted
- (IBAction)Done:(id)sender {
[someClassObject SetDataOne: #”whatever text”];
[someClassObject SetDataTwo: #”whatever text”];
[someClassObject SetDataThree: #”whatever text”];
[someClassObject SaveSomeData];
Error Msg for all the above: ”Use of Undeclared Identifier ’someClassObject’
}
#end
Comment: You can see the error message I get at the end of the code above. I have no clue what I am doing wrong. I have looked at a lot of examples on how to create and call classes, but cannot seem anything that solves my problem. Also, I see that some of the put the ”SomeClass *someClassObject = [[SomeClass alloc] init];” in the ”main.m file”. If I understand correctly, that file is the first one to load when app starts. If so, then I cannot place it there as I will have to create instances of my class in several different views and other times than when the app starts. That is why I have placed it in the viewDidLoad-method.

Answer 1

A couple of thoughts:
You've made someClassObject a local variable of the viewDidLoad method. Looks like you meant to make it a class instance variable (or, better, a private class property, which will have the instance variable synthesized for you). Thus:
#interface SomeView ()
#property (nonatomic, strong) SomeClass *someClassObject;
#end
#implementation SomeView
- (void)viewDidLoad
{
[super viewDidLoad];
self.someClassObject = [[SomeClass alloc] init];
}
- (IBAction)done:(id)sender {
[self.someClassObject setDataOne: #"whatever text"];
[self.someClassObject setDataTwo: #"whatever text"];
[self.someClassObject setDataThree: #"whatever text"];
[self.someClassObject saveSomeData];
// should resolve the Error Msg for all the above: ”Use of Undeclared Identifier ’someClassObject’
}
BTW, as a matter of convention, your method names should start with a lowercase letter (e.g. setDataOne not SetDataOne, done rather than Done, etc.), as illustrated above.
If you're going to write your own setters, setDataOne, setDataTwo, etc., you might as well remove those three instance variables, remove your three setData___ methods, and replace the three instance variables with class properties (and let the compiler synthesize not only the instance variables, but the setters, too).

Answer 2

someClassObject is set inside viewDidLoad and because it is not stored anywhere inside the view will be deleted at the end of that very same method

Answer 3

You should add your object inside each header file's interface section like this:
SomeView.h
#import <UIKit/UIKit.h>
#import "HeadViewController.h"
#import "SomeClass.h"
#interface SomeView : UIViewController
{
SomeClass *someClassObject;
}
// contains stuff not needed to show here
- (IBAction)Done:(id)sender;
#end
Then when you instantiate someClassObject inside ViewDidLoad it will persist throughout that view.