Question

In this example my NSDictionary initializes with 0 key/value pairs, as shown in my debugger. It will initialize properly when I do the exact same thing in my ViewController but I would much prefer to stick to MVC design and have the NSDictionary in my model.

ShakespeareViewController.h

    #import <UIKit/UIKit.h>

    @interface ShakespeareViewController : UIViewController
    @property (weak, nonatomic) IBOutlet UILabel *sonnetDisplay;

    @end

ShakespeareViewController.m

    #import "ShakespeareViewController.h"
    #import "ShakespeareModel.h"

    @interface ShakespeareViewController ()
    @property (nonatomic, strong) ShakespeareModel *sonnet;
    @end

    @implementation ShakespeareViewController
    @synthesize sonnetDisplay = _sonnetDisplay;
    @synthesize sonnet = _sonnet;


    - (IBAction)sonnetButton:(UIButton *)sender 
    {
        self.sonnetDisplay.text = [self.sonnet grabSonnet:@"19"];
    }

    @end

ShakespeareModel.h

    #import <Foundation/Foundation.h>

    @interface ShakespeareModel : NSObject

    -(NSString *)grabSonnet:(NSString *)atNumber;

    @end

ShakespeareModel.m

    #import "ShakespeareModel.h"

    @interface ShakespeareModel()
    @property (nonatomic, strong) NSDictionary *sonnets;
    @end

    @implementation ShakespeareModel

    @synthesize sonnets = _sonnets;

    -(NSDictionary *)sonnets 
    {
        if (!_sonnets)
        {
            _sonnets = [[NSDictionary alloc] initWithObjectsAndKeys:@"19", @"19", nil];
        }
        return _sonnets;
    }

    -(NSString *)grabSonnet:(NSString *)atNumber
    {
        NSString *chosenSonnet = [self.sonnets objectForKey:@"19"];
        return chosenSonnet;
    }

    @end

Any ideas on what I am doing wrong are greatly appreciated. I can’t see why this wouldn’t initialize with the object 19 at key value 19.

Answer 1

I don’t see any place where you set the view controller’s sonnet property to an instance of ShakespeareModel — so when you call grabSonnet: you’re sending a message to nil (and thus getting nothing back.

You should put self.sonnet = [[ShakespeareModel alloc] init] in your view controller some time before you call grabSonnet:… probably in the initializer or in -viewDidLoad.