Trying to put a global NSMutable Array in Objective C

Question

I`m making an exercise, i have 2 classes Songs and Playlist, in the program i can put songs in playlist and everything is working fine, but i need to make a master playlist with all the songs that are in all the normal playlist and there is the problem.

Here is the code

    //
//  main.m
//  MyItunes
//
//  Created by Rodrigo López on 6/29/12.
//  Copyright (c) 2012 ITQ. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Songs.h"
#import "PlayList.h"

int main (int argc, const char * argv[])
{

    @autoreleasepool {

        Songs *mySong1 = [Songs new];
        Songs *mySong2 = [Songs new];
        Songs *mySong3 = [Songs new];
        PlayList *myPlayList1=[[PlayList alloc]initWithName:@"First"];
        PlayList *myPlayList2=[[PlayList alloc]initWithName:@"Second"];


[mySong1 setTitle:@"Back In Black" setArtist:@"AC/DC" setAlbum:@"Back In Black"               setPlayt:@"4:16"];
[mySong2 setTitle:@"Medicate" setArtist:@"AFI" setAlbum:@"Crash Love" setPlayt:@"4:21"];
[mySong3 setTitle:@"Rucci" setArtist:@"Austin TV" setAlbum:@"La ultima noche" setPlayt:@"4:39"];

        [myPlayList1 addSong:mySong1];
        [myPlayList1 addSong:mySong2];
        [myPlayList2 addSong:mySong3];

        [myPlayList1 showPlayList];
        [myPlayList2 showPlayList];

         [myPlayList1 showPlayList];
         [myPlayList1 showAllSongs];

       }
    return 0;
}

    //
//  PlayList.m
//  MyItunes
//
//  Created by Rodrigo López on 6/29/12.
//  Copyright (c) 2012 ITQ. All rights reserved.
//

#import "PlayList.h"



@implementation PlayList


@synthesize playListarray,playListName;




-(id) initWithName: (NSString *) name  
{
  if(self)
  { 
    playListName = [NSString stringWithString: name]; 
    playListarray = [NSMutableArray array];
    playlistMaster=[NSMutableArray array ];
  }
    return self;
}




-(void) addSong: (Songs *) theSong
{



    [playListarray addObject:theSong];  

    [playlistMaster addObject:theSong];  

}

-(void) showPlayList
{
     NSLog(@"Play List: %@", self.playListName);
    for(Songs *theSong in playListarray)
    {
        NSLog(@"%@", theSong.title);
    }


}

-(void) showAllSongs
{
    NSLog(@"Play List: Master");
    for(Songs *theSong in playlistMaster)
    {
        NSLog(@"%@", theSong.title);
    }
}



-(NSUInteger) entries 
{
    return [playListarray count]; 
}

-(void) remove: (Songs *) theSong 
{

    [playListarray removeObjectIdenticalTo:theSong];
}


@end

The problem is with the NSMutable array, i want to declare the array globally, but i dont know how to do it, here is the output of this program:

2012-06-29 19:24:06.061 MyItunes[17184:707] Play List: First
2012-06-29 19:24:06.080 MyItunes[17184:707] Back In Black
2012-06-29 19:24:06.083 MyItunes[17184:707] Medicate
2012-06-29 19:24:06.084 MyItunes[17184:707] Play List: Second
2012-06-29 19:24:06.085 MyItunes[17184:707] Rucci
2012-06-29 19:24:06.089 MyItunes[17184:707] Play List: First
2012-06-29 19:24:06.090 MyItunes[17184:707] Back In Black
2012-06-29 19:24:06.091 MyItunes[17184:707] Medicate
2012-06-29 19:24:06.091 MyItunes[17184:707] Play List: Master
2012-06-29 19:24:06.092 MyItunes[17184:707] Back In Black
2012-06-29 19:24:06.093 MyItunes[17184:707] Medicate

So in play list master, its missing Rucci song, hope you can help me, thank you very much, i appreciate it

score 0 · Answer 1 · edited May 23 '17 at 11:56

I would make your playlistMaster a "static variable" of the PlayList implementation file as described at: Objective C Static Class Level variables. You just declare and initialize it the .m file outside of any other methods. (Don't forget to make sure it is retained.)

I should also note that there are some memory issues in your PlayList class. In particular, your initializer code should retain the member variables, like:

-(id) initWithName: (NSString *) name
{
    if (self = [super init]) {
        playListName = [[NSString stringWithString: name] retain];   // NOTE:  You could also do:  [[NSString alloc] initWithString: name];
        playListarray = [[NSMutableArray array] retain];    // NOTE:  You could also do:  [[NSMutableArray alloc] init];
        playlistMaster = [[NSMutableArray array] retain];    // ditto
    }
    return self;
}

If you do this, you will need to add a dealloc method that releases each of these. But if you don't they may be released before you try to use them.

ohhh putting the static variable was great.... it works, thanks for your time and help!! — Rodrigo López, Jun 30 '12 at 01:34

Trying to put a global NSMutable Array in Objective C

1 Answers1