How to initialize array in objective-c

Question

Very basic question :)

I have to initialize an array in objective-c. I will further use that array value in table view. I have a listing of chapters and I have written it as hardcoded like below.

    NSArray *tableList;

tableList = [[NSArray alloc]initWithObjects:@"Chapter 1",@"Chapter 2",@"Chapter 3",@"Chapter 4",@"Chapter 5",nil];

But now I have a indexed array which is keeping chapters details. below is the code of array which is holding value.

 extern NSArray *wallvalue;

    for (NSDictionary *chapter in wallvalue) {
        NSString *chapterName = [person objectForKey:@"chapters"];
        if([chapterName length] >0)
        {

            NSLog(chapterName);
        }
    }

Now I want to show these chapterName in my tablelist. How will I do this ?

Thanks in advance.

Joe · Accepted Answer · 2014-09-07 18:17:11Z

3

NSMutableArray *tableList = [[NSMutableArray alloc] initWithCapacity:[wallvalue count]];
for (NSDictionary *chapter in wallvalue) {
    NSString *chapterName = [person objectForKey:@"chapters"];
    if([chapterName length] >0)
    {
        [tableList addObject:chapterName];
    }
}

edited Sep 7, 2014 at 18:17

user463535

answered Jun 22, 2011 at 13:38

Joe

57.2k9 gold badges130 silver badges136 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Ajay_Kumar Over a year ago

@Joe, Thanks for reply. But I am seeing blank on table view. I think strings are not attaching with tablelist. Please check once.

Joe Over a year ago

Shouldn't be empty if you were able to log the chapter name before. Something is nil somewhere, also check Deepak's edit for filtering using a predicate.

Ajay_Kumar Over a year ago

@Joe. Yes you right it was being empty. Now I am getting an exception. I think this is happening due to NULL statement.

Joe Over a year ago

You need to do an NSNull check on chapterName. if(![[NSNull null] isEqual:chapterName] && [chapterName length]) of if you have control over the dictionary just dont add the key if it is going to be null.

Deepak Danduprolu Over a year ago

I don't think that is the case. The predicate handles [NSNull null] instance.

|

Deepak Danduprolu · Accepted Answer · 2011-06-22 13:52:43Z

0

Shouldn't you just be doing,

cell.textLabel.text = [[wallvalue objectAtIndex:indexPath.row] objectForKey:@"chapters"];

EDIT If you are interested in only those chapters which have a name, then filter all objects that don't have a proper name and then do the thing above,

NSArray * filteredChapters = [wallvalue filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"chapters LIKE '?*'"]];

[..]

cell.textLabel.text = [[filteredChapters objectAtIndex:indexPath.row] objectForKey:@"chapters"];

edited Jun 22, 2011 at 13:52

answered Jun 22, 2011 at 13:38

Deepak Danduprolu

44.6k12 gold badges103 silver badges106 bronze badges

4 Comments

Joe Over a year ago

Ajay is checking the length of the chapter so another array will be needed to pass the correct number of rows in the case of using a UITableView.

Deepak Danduprolu Over a year ago

Yeah I updated it so that we can filter all those dictionaries that have a chapter name.

Joe Over a year ago

There we are gotta love predicates.

Ajay_Kumar Over a year ago

Yes Now I am getting but I am getting on excepetion which is -[NSNull length]: unrecognized selector sent to instance 0xe515e8 2011-06-22 19:36:20.183 FEngine[2636:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSNull length]: unrecognized selector sent to instance 0xe515e8'. Is it not cheking length properly ?

Collectives™ on Stack Overflow

How to initialize array in objective-c

2 Answers 2

6 Comments

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

6 Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related