CaculatorAppDele.h

#import <Cocoa/Cocoa.h>
#import "CaculatorBrain.h"
@interface CaculatorBrainAppDelegate : NSObject <NSApplicationDelegate>

// the outlet of the label
@property (weak) IBOutlet NSTextFieldCell *display;

@property (assign) IBOutlet NSWindow *window;

@property (nonatomic) BOOL userIsInMiddleOfEntering;

@property (nonatomic,strong) CaculatorBrain * barin;


@end

CaculatorAppDele.m

#import "CaculatorBrainAppDelegate.h"
#import "CaculatorBrain.h"



@implementation CaculatorBrainAppDelegate

// this the label target outlet 
@synthesize display = _display;
// this the windows target outlet
@synthesize window = _window;
@synthesize barin=_barin;

@synthesize userIsInMiddleOfEntering=_userIsInMiddleOfEntering;

- (IBAction)enterPressed:(NSButton*)sender {
    [self.barin pushOperand:[self.display.title doubleValue]];
    self.userIsInMiddleOfEntering=NO;
}

// action of the action
- (IBAction)operationPressed:(NSButton*)sender 
{

    double result=[self.barin performOperation:sender.title];
    NSString* resultString  =[NSString stringWithFormat:@"%@",result];
    self.display.title=resultString;
    
    
}

// action for the button
- (IBAction)digitalPressed:(NSButton*)sender 
{
    NSString* digit=[sender title];
    
    
    if(self.userIsInMiddleOfEntering){
    [self.display setTitle:[self.display.title stringByAppendingString:[sender title]]];
    }
    else{
        self.display.title=digit;
        self.userIsInMiddleOfEntering=YES;
    }
    
    NSLog(@"digit: %@ has pressed!",digit);
}

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    // Insert code here to initialize your application
}

@end

CaculatorBrain.h

#import <Foundation/Foundation.h>

@interface CaculatorBrain : NSObject


- (void) pushOperand:(double)operand;
- (double) performOperation:(NSString*) operation;
- (double) popPerand;

@property (readonly) id program;

+ (double) ruanProgram:(id) program;
+ (NSString*) descriptionOfTheProgram:(id) program;

@end

CaculatorBrain.m

#import "CaculatorBrain.h"

@interface CaculatorBrain()

@property (nonatomic)NSMutableArray* operandStack;

@end

@implementation CaculatorBrain

@synthesize operandStack=_operandStack;
@synthesize program=_program;
-(NSMutableArray*) operandStack{
    if(_operandStack==nil){
        _operandStack=[[NSMutableArray  alloc] init];
    }
    return _operandStack;
}

- (void) pushOperand:(double)operand
{
    
    NSNumber* operandObject=[NSNumber numberWithDouble:operand];
    NSLog(@"add to stack: %@",operand);
    [self.operandStack addObject:operandObject];

}

- (double) performOperation:(NSString*) operation
{
    [self.operandStack addObject:operation];
    return [CaculatorBrain ruanProgram:self.program];
}

-(id) program 
{

return [self.operandStack copy];
}

+(NSString*) descriptionOfTheProgram:(id)program{
    return @"implement of the program";
}

+(double)runProgram:(id)program{
    NSMutableArray* stack;
    if([program isKindOfClass:[NSMutableArray class]]){
        stack=[program mutableCopy];
    }
    return [self popOperandOfStack:stack];
}

+(double) popOperandOfStack:(NSMutableArray*)stack{
    double result=0;
    
    id topStack=[stack lastObject];
    if (topStack){
        [stack removeObject:topStack];
        
    }
    if ([topStack isKindOfClass:[NSNumber class]])
    {
        result=[topStack doubleValue];
    }
    if([topStack isKindOfClass:[NSString class]])
    {
        NSString* operation = topStack;
        if([operation isEqualToString:@"+"]){
            result=[self popOperandOfStack:stack]+[self popOperandOfStack:stack];
        }
        else if([@"-" isEqualToString:operation])  {
            result=[self popOperandOfStack:stack]-[self    popOperandOfStack:stack];
        }
        else if([@"*" isEqualToString:operation]){
            result=[self popOperandOfStack:stack]*[self popOperandOfStack:stack];
        }
        else if([@"/" isEqualToString:operation]){
            result=[self popOperandOfStack:stack]/[self popOperandOfStack:stack];
        }

        
    }
    return result;
}
@end