Getter和Setter int值（NSObject）没有从一个ViewController传递到另一个

Question

I'm building a game with 3 different level difficulties (Easy, Medium, & Delete) I have 2 ViewControllers and 1 NSObject class that I'm using to set and get the game difficulty value (0=easy, 1=Medium, 2=Delete(hard). Within context of how I'm doing it, I've research and tried many variations with no success. NOTE: I have tried to code this, but have since stripped out that part of the code because it wasn't working. I'm somewhat familiar with NSUserDefaults, so if that's a better solution, please advise. I may need a little direction on setting that up, though.
- ViewController 1 (RewindSettingsViewController): I have 3 buttons: Easy, Medium, Delete. User taps button, they go to ViewController 2
- ViewController 2 (RewindGameViewController): This is the actual game with a Start button. This is where I'm hung up; getting the difficulty passed into this view.
CODE:
.h - GameManager : NSObject

+(void) setDifficulty:(int)difficulty;
+(int) getDifficulty;

.m - GameManager

static int _difficulty;

+(void)setDifficulty:(int)difficulty {
    _difficulty = difficulty;
}

+(int)getDifficulty {
    return _difficulty;
}

(VC1) .h - RewindSettingsViewController : UIViewController

@property (nonatomic, strong) IBOutlet UIButton *easyModeButton;
@property (nonatomic, strong) IBOutlet UIButton *mediumModeButton;
@property (nonatomic, strong) IBOutlet UIButton *hardModeButton;

-(IBAction)easyMode;
-(IBAction)mediumMode;
-(IBAction)hardMode;

.m - RewindSettingsViewController

-(IBAction)easyMode {
    [GameManager setDifficulty:0];
}

-(IBAction)mediumMode {
    [GameManager setDifficulty:1];
}

-(IBAction)hardMode {
    [GameManager setDifficulty:2];
}

(VC2) .h - RewindGameViewController : UIViewController

no code here for difficulty settings

.m - RewindGameViewController

At this point, _difficulty is of course still nil. My question marks below are my pain points

?: How to get the difficulty value stored in "setDifficulty" into "getDifficulty (_difficulty)" and properly call it in the IF statement?
?: I'm thinking _difficulty should be in the IF statements, but with everything I'm trying, syntax keeps barking at me.

-(void)placeObjectsRewind {

    randomTopObjectRewind = arc4random() %350;  
    randomTopObjectRewind = randomTopObjectRewind - 228;

    if (?) {

    randomBottomObjectRewind = randomTopObjectRewind + 700; //LEVEL DIFFICULTY: EASY
        objectTopRewind.center = CGPointMake(0, randomTopObjectRewind);
        objectBottomRewind.center = CGPointMake(0, randomBottomObjectRewind);

    } else if (?) {

    randomBottomObjectRewind = randomTopObjectRewind + 665; //LEVEL DIFFICULTY: MEDIUM
        objectTopRewind.center = CGPointMake(0, randomTopObjectRewind);
        objectBottomRewind.center = CGPointMake(0, randomBottomObjectRewind);

    } else if (?) {

        randomBottomObjectRewind = randomTopObjectRewind + 635; //LEVEL DIFFICULTY: DELETE (HARD)
            objectTopRewind.center = CGPointMake(0, randomTopObjectRewind);
            objectBottomRewind.center = CGPointMake(0, randomBottomObjectRewind);
    }
}

Answer 1

Instead of

static int _difficulty;

type this into your GameManager.h

@property int difficulty;

You don't have to write the Setter and Getter by yourself, the property-statement do this for you. The Getter/Setter is stored in the instance of GameManager you use. So get the instance of you GameManager and there you set like this:

[MyGameManagerInstance setDifficulty:0]; 

and get like

[MyGameManagerInstance difficulty];

Due to the fact that the difficulty-property is in the .h file, it's part of the Class's API which you can access from other ViewController or Classes.

EDIT: Like you said, you could do this also with the NSUserDefaults. Just put it in like this:

[[NSUserDefaults standardUserDefaults] setInteger:1 forKey:@"Difficulty"];

and get it like this:

int myInt = [[NSUserDefaults standardUserDefaults] integerForKey:@"Difficulty"];

Answer 2

Since you've made the methods you want to use class methods, the syntax is going to be similar to if ([GameManager getDifficulty] == 0) etc.

(As a style point, you would usually drop the "get" in Objective-C and just name the method to return a value difficulty .)