Question

I have several files to be saved in the Documents folder, this list of files put in a mutable array. The files must remain in the memory of the iPhone application also closed. The first file is saved, but when I change view controllers and then go back the mutable array becomes empty. How do I keep the data in memory in the Documents folder?

in DetailExpViewController.h

  //....
  @property (nonatomic, strong)NSMutableArray *arrayFavorites;
  @property (nonatomic, assign)BOOL existsArray;
  //....
  @end

in DetailExpViewController.m

- (void)viewDidLoad
 {
      //.....
      if (!self.existsArray){
          /*when I load the view controller this array is always nil even 
            has already  been created*/

           self.arrayFavorites =[[NSMutableArray alloc]init];
     }else{
          NSLog(@"The array exists");
      }
      //....
 }

 -(void) addFavorites:(id)sender{

     //.....
   NSArray *paths = NSSearchPathForDirectoriesInDomains
  (NSDocumentDirectory, NSUserDomainMask, YES);
   NSString *documentsDirectory = [paths objectAtIndex:0];

   NSString * text= [NSString stringWithFormat:@"%@.txt",self.name];
   NSString * documentsPath = [documentsDirectory stringByAppendingPathComponent: text];

   [self.arrayFavorites addObject:text];
   [self.arrayFavorites writeToFile:documentsPath atomically:YES];
   self.existsArray=YES;

   for (id obj in self.arrayFavorites) {

    NSLog(@"%@", self.arrayFavorites);
    //only writes the file at the time, then it is deleted

  }

}

Answer 1

U can save NSArray in Document Directory like this.

Note : saving and retrieving filename remains same.

Its also easy retrieve saved array from doc dir.

EDIT : If data is complex and large better use SQLITE.

---

EDIT : In view Controller's Add to favourite button click event:

 //check favourite saved in doc dir
 if(!saved) //not saved
   //NSMutableArray has not data first time
   //[NSMutableArray addObject:newFavourite];
   //save new data in doc dir
 else // saved
   //firstly retrieve data from doc dir as NSMutableArray
   //[NSMutableArray addObject:newFavourite];
   //Now save again NSMutableArray in doc dir.

By following these instruction files remain permanently in the Documents folder.