objective C in Xcode - NSLog and access other class property

Question

I am a total newbie in Objective-C and Xcode (new to programming as well). I am trying to build a simple card game so I created a Cards class with properties and instance methods and imported its header file into "Viewcontroller.m".

However, I do not understand two things:

1. Why the NSLog in the "Cards.m" is not displaying in the console as I compile. But NSLog in "Viewcontroller.m" displays.

2. Seems I can not call the Cards class ( NSMutableArray ) property. Even I initialized it without error in "Cards.m", in "Viewcontroller.m", the array is still empty.

Very appreciate your helps because I am very struggling!

Cards.h:

@interface Cards : NSObject

@property (strong, nonatomic) NSMutableArray* contents;

-(void)makeContents;

@end

Cards.m:

#import "Cards.h"
@interface Cards()

@end

@implementation Cards

@synthesize contents;

-(id)init{
    if(self==[super init]){
        contents = [[NSMutableArray alloc]initWithCapacity:53];
    }

    return self;
}

-(void) makeContents{
     NSArray* suits = @[@"♥︎",@"♠︎",@"♣︎",@"♦︎" ];

     NSArray* ranks = [[NSArray alloc]initWithObjects:@"A",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"J",@"Q",@"K", nil];
     for(NSString* suiting in suits){
        for(NSString* ranking in ranks){
            NSString* cards = [NSString stringWithFormat:@"%@ %@", ranking,suiting];
            [contents addObject:cards];

            NSLog(@"%@", contents);//not displaying in console
        }
    }
}

@end

ViewController.m:

#import "ViewController.h"
#import "Cards.h"

@interface ViewController ()

@property (weak, nonatomic) IBOutlet UILabel *flipCount;
@property (nonatomic) int numberOfFlip;

@end

@implementation ViewController

-(void)viewDidLoad{
    Cards* cards = [[Cards alloc]init];

    NSLog(@"%@", cards.contents); //displaying in console, the contents is an empty array still? why??
}

- (IBAction)flipCard:(UIButton *)sender {
}

@end

Answer 1

You create and define the method makeContents but never actually call it anywhere. Try calling it in your viewDidLoad method:

-(void)viewDidLoad{
    [super viewDidLoad];

    Cards* cards = [[Cards alloc]init];
    [cards makeContents];
     NSLog(@"%@", cards.contents); //displaying in console, the contents is an empty array still? why??

}

Answer 2

You have a few issues.

1. You should use = , not == to assign self to [super init] .
2. The Cards init method should call makeContents to set itself up.

Update your init method like this:

-(id)init{
    self = [super init];
    if (self) {
        contents = [[NSMutableArray alloc]initWithCapacity:53];
        [self makeContents];
    }

    return self;
}

This also means that makeContents should only be called by the Cards class itself. So you should remove the declaration of - (void)makeContents from the .h file.

Also, using @synthesize as you have it is unnecessary. Simply remove that line. And try to find a more up-to-date tutorial that doesn't use such outdated code.