Question

I am trying to keep close to the MVC approach to programming in an objective C application.

I have a model class and two View Controllers.

@interface Disc : NSObject {


NSString *discType;
NSNumber *capacity; }


@property (nonatomic,retain) NSString *discType;
@property (nonatomic,retain) NSNumber*capacity;

@implementation Disc

@synthesize discType,capacity;

Then for View Controller A

@interface DiscTypeViewController : SecondLevelViewController {

NSString *discTypeSub;
}

@property (nonatomic,retain) NSString *discTypeSub;
@end


@implementation DiscTypeViewController

@synthesize discTypeSub;

Now, I know I can access the members of the model (disc) class from View controller A

Disc *disc1 = [[Disc alloc]init];

[disc1 setDiscType:@"DVD"]; 

discTypeSub = [disc1 discType];

This returns the value “DVD” which is fine.

The question is, how can my Second View Controller access that same String that returned
“DVD”. There’s no point in initializing a new instance of Disc. I need the values that were
created from View Controller A calling the setter/getter methods of the Disc class.

What is the best design approach for such a scenario, any info would be much appreciated.

Answer 1

You could create some sort of a context object. Most likely it would be a SingleTon or Factory (static getters/setters). You can have a dictionary with keys @”DVD” or @”BlueRay” with values of type Disk.
Please consider that these objects will reside in your memory while stored in you cache dictionary. Consider to use NSCache if you target iOS4.