call NSString whit multiple parameters

Question

I am a beginner and maybe it is a trivial question. I have this method:

-(NSString *)getInfoFormediaItem:(MPMediaItemCollection *)list {    
NSString *trackCount;

if ([list count] > 0) {
    trackCount = [NSString stringWithFormat:NSLocalizedString(@"%lu Songs", @""), (unsigned long)[list count]];
} else if([list count] == 1) {
    trackCount = [NSString stringWithFormat:NSLocalizedString(@"1 Song", @"")];
} else {
    trackCount = [NSString stringWithFormat:NSLocalizedString(@"0 Song", @"") ];
}

return [NSString stringWithFormat:@"%@", trackCount];
}

I would like to call it here with a MPMediaItemCollection:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];

if( cell == nil )
{
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"cell"];
} 

MPMediaQuery *playlistsQuery = [MPMediaQuery playlistsQuery];
NSArray *playl = [playlistsQuery collections];
MPMediaItem *rowItem = [playl objectAtIndex:indexPath.row];
MPMediaItemCollection * collection = [[MPMediaItemCollection alloc] initWithItems:[NSArray arrayWithObject:rowItem]];

cell.detailTextLabel.text = [self getInfoFormediaItem:collection];
}

I would like to get the number of tracks in each playlist. It doesn't work. How do I fix? Thanks in advance!

Answer 1

1. Why are you using performSelector:withObject:? Just call the method directly:

   cell.detailTextLabel.text = [self getInfoFormediaItem:collection];
   

2. Why are you passing nil to the withObject: parameter? That's why your code goes to the else. list is nil so [list count] will always be 0. You need to pass an actual instance of a MPMediaItemCollection.

3. Why are you needlessly using stringWithFormat: for the 1 and 0 count checks? Just do:

   -(NSString *)getInfoFormediaItem:(MPMediaItemCollection *)list {    
       NSString *trackCount;
   
       if ([list count] > 1) {
           trackCount = [NSString stringWithFormat:NSLocalizedString(@"%lu Songs", @""), (unsigned long)[list count]];
       } else if([list count] == 1) {
           trackCount = NSLocalizedString(@"1 Song", @"");
       } else {
           trackCount = NSLocalizedString(@"0 Song", @"");
       }
   
       return trackCount;
   }
   

4. Based on your updated question, your cellForRowAtIndexPath code isn't correct for the getting the media collection. The collectionsmethod returns an array of MPMediaCollection objects, not MPMediaItem objects. You need:

   MPMediaQuery *playlistsQuery = [MPMediaQuery playlistsQuery];
   NSArray *playl = [playlistsQuery collections];
   MPMediaItemCollection *collection = playl[indexPath.row];
   

   Now you can use collection when you call getInfoFormediaItem:.

Answer 2

You simply don't need to call this statement:

cell.detailTextLabel.text =  [self performSelector:@selector(getInfoFormediaItem:) withObject:nil];

in your "getInfoFormediaItem"method. You do that in your "cellforrowataIndexPath" method when you define the cell,just call like this:

cell.detailTextLabel.text = [self getInfoFormediaItem:This_Is_A_List_You_Wanna_Pass_To_The_Method];

and you should be good to go.

Answer 3

In addition to the problems pointed out by other posters, your if statement will not work as you want it to:

if ([list count] > 0) {
    trackCount = [NSString stringWithFormat:NSLocalizedString(@"%lu Songs",
    @""), (unsigned long)[list count]];
} else if([list count] == 1) {
    trackCount = [NSString stringWithFormat:NSLocalizedString(@"1 Song", @"")];
} else {
    trackCount = [NSString stringWithFormat:NSLocalizedString(@"0 Song", @"") ];
}

The "if ... >0" clause will match first, before checking for a value of 1, since 1 is > 0. Thus the "if ... == 1" will never evaluate as true. You need to reorder that if statement:

if ([list count] == 1) {
    trackCount = NSLocalizedString(@"1 Song", @"");
else if ([list count] > 0) {
    trackCount = [NSString stringWithFormat:NSLocalizedString(@"%lu Songs",
    @""), (unsigned long)[list count]];
} 
else 
{
    trackCount = NSLocalizedString(@"0 Songs", @"");
}