Question

I am making a program and i have to initialize and reinitialize my NSString variable.I wrote related code but when am trying to reinitialize my NSString variable my program is being crashed. My macdelegate.h file are listed here.

@interface MacCalculatorAppDelegate : NSObject <UIApplicationDelegate> {

    UIWindow *window;

    UIButton *digitPressed;

    UIButton *operatorPressed;

    NSString *waitingOperation;
}
@property (nonatomic, retain) IBOutlet UIWindow *window;

@property ( retain) NSString* waitingOperation;

-(IBAction) digitPressed:(UIButton *)sender;

-(IBAction) operatorPressed:(UIButton *)sender;

@end

And part of code of my macdelegate.m file are listed here.

- (id) init 

    {

    if (self = [super init])
        {

       self.waitingOperation=@"not set";//@"not set";           

        }

        return self;

    }


-(IBAction) digitPressed:(UIButton *)sender {

if(![@"not set" isEqualToString:waitingOperation])

    {
 waitingOperation=@"not set";//@"not set";

}
}

-(IBAction) operatorPressed:(UIButton *)sender {

    NSString *operand=[[sender titleLabel] text];

    resultDisplay.text=operand;

    if([@"+" isEqualToString:operand])

    {    

 waitingOperation=@"+";//@"not set";        

    }

}

- (void)dealloc {

    [waitingOperation release];

    [window release];

    [super dealloc];

}

My all listed codes are above when i am running my program first time this is initialize well but when i am trying to reinitialize my program is doing nothing i suppose this is being crashed.
I am new with Objective-C help me.

Thanks in advance.

Answer 1

I think, you have forgotten synthesize statement for your retaining variable waitingOperation and using it as self.waitingOperation would cause a crash, because run time system could not find a setter function for the property waitingOperation

Add @synthesize waitingOperation; in your implementation file.

Use the modified code let me know if you still get the crash.

-(IBAction) digitPressed:(UIButton *)sender 
 {
    if(![ self.waitingOperation isEqualToString:@"not set"])
    {
     self.waitingOperation=@"not set";//@"not set";
   }
}

-(IBAction) operatorPressed:(UIButton *)sender {

    NSString *operand=[[sender titleLabel] text];

    resultDisplay.text=operand;

    if([operand isEqualToString:@"+"])
    {    

      self.waitingOperation=@"+";//@"not set";        
    }

}