intialization with a nibFIle failed

Question

Hi, I have a problem. I try to initialize a variabile in a classViewController created inside a xib file. I try with the code below but when i append a object to array, these array isn't initialized. Can you help me? thanks and sorry for my english.

#import <UIKit/UIKit.h>

@interface AccelerometroViewController : UIViewController <UIAccelerometerDelegate, UITextFieldDelegate, UIAlertViewDelegate>{

    //.....     

    NSMutableArray *arrayPosizioni;
    NSMutableArray *arrayPosizioniCorrenti;

    NSString *nomePosizioneCorrente;

}

-(IBAction)salvaPosizione;


//...
@property (nonatomic, assign)   NSMutableArray      *arrayPosizioni;
@property (nonatomic, assign)   NSMutableArray      *arrayPosizioniCorrenti;

@property (nonatomic, assign)   NSString      *nomePosizioneCorrente;

@end



#import "AccelerometroViewController.h"
#import "Position.h"

@implementation AccelerometroViewController



float actualX;
float actualY;
float actualZ;


@synthesize arrayPosition;
@synthesize arrayCurrentPosition;

@synthesize nameCurrentPosition;

    -(id)init {
        self = [super init];
        if (self != nil) {
            arrayPosition = [[NSMutableArray alloc]init];
            arrayCurrentPosition = [[NSMutableArray alloc]init];
            nameCurrentPosition = [NSString stringWithFormat:@"noPosition"]; 
            actualX = 0;
            actualY = 0;
            actualZ = 0;
        }
        return self;
    }


    -(void)updateTextView:(NSString*)nomePosizione
    {
        NSString *string = [NSString stringWithFormat:@"%@", nameCurrentPosition];
        textEvent.text = [textEvent.text        stringByAppendingString:@"\n"];
        textEvent.text = [textEvent.text        stringByAppendingString:string];
    }


    -(IBAction)savePosition{

        Posizione *newPosition;
        newPosition = [[Position alloc]init];

        if([newPosition     setValue:(NSString*)fieldNomePosizione.text:(float)actualX:(float)actualY:(float)actualZ]){
       //setValue is a method of Position. I'm sure that this method is correct
            UIAlertView *alert = [[UIAlertView  alloc] initWithTitle:@"Salvataggio Posizione" message:@"Posizione salvata con successo" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:nil];
            [alert  show];
            [alert  release];           
            [arrayPosition  addObject:newPosition];
        }
        else{
            UIAlertView *alert = [[UIAlertView  alloc] initWithTitle:@"Salvataggio osizione" message:@"Errore nel salvataggio" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:nil];
            [alert show];
            [alert release];
        }
   }

 - (void) initialise {
     arrayPosition = [[NSMutableArray alloc] init];
     arrayCurrentPosition = [[NSMutableArray alloc] init];
     nameCurrentPosition = @"noPosition"; 
     actualX = 0;
     actualY = 0;
     actualZ = 0;
 }

 - (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)nibBundle {
     if (self = [super initWithNibName:nibName bundle:bundle]) {
         [self initialise];
     }
} 

Answer 1

In addition to Felix's comment regarding the mis-naming, your properties are wrong too. Objects need to be retained or copied, not assigned (in most cases) so that you're certain their value won't go away. You need to have ownership of them. As such I would use the following:

@property (nonatomic, readwrite, retain)   NSMutableArray *arrayPosition;
@property (nonatomic, readwrite, retain)   NSMutableArray *arrayCurrentPosition;
@property (nonatomic, readwrite, copy)   NSString *nameCurrentPosition;

Then, since you've retained something you're responsible for releasing it. As such you'll need a dealloc method to do that.

-(void)dealloc {
    self.arrayPosition = nil;
    self.arrayCurrentPosition = nil;
    self.nameCurrentPosition = nil;
    [super dealloc];
}