Having problems with Array

Question

SO here's my setup. I have an object called radiostations where I have several strings like callsign, frequency declared and an NSMutableArray called amStationInfo. On my viewcontroller, I access an SQLite database which populates the an array like so...

radiostations.h

@interface radiostations : NSObject {

    NSString *format;
    NSString *city;
}

@property (nonatomic, retain) NSString *format;
@property (nonatomic, retain) NSString *city;

ViewController.m

radiostations *amStationClass = [[radiostations alloc] init];
NSMutableArray* amStationInfo = [[NSMutableArray alloc] init];

while (sqlite3_step(statement) == SQLITE_ROW)
    {
    NSString *cityField = [[NSString alloc] initWithUTF8String:
                                   (const char *) sqlite3_column_text(statement, 10)];
    NSString *formatField = [[NSString alloc] initWithUTF8String:
                                    (const char *) sqlite3_column_text(statement, 0)];
    [amStationInfo addObject:amStationClass];
                    [amStationClass setCity:cityField];
                    [amStationClass setFormat:formatField];
    }
[tabView reloadData];
sqlite3_finalize(statement);

and then I populate a UITableView

NSString *cityValue = [(radiostations *)[amStationInfo objectAtIndex:indexPath.row] city];
NSString *formatValue = [(radiostations *)[amStationInfo objectAtIndex:indexPath.row] format];
cityLabel.text = cityValue;
formatLabel.text = formatValue;

Initially I was dealing with a few Arrays and this worked just fine. I then changed it so that I was only dealing with one array using a class object and now it's not working. I know the SQLite query and what not works so Im not having any problems with that. It seems as though the array does not get populated.

Your naming is a mess; radiostations should be RadioStations, amStationClass should be amStation (it isn't a class, it is an instance), amStationInfo should probably be amStationsArray, cityField should be city or cityName, etc... also, if you aren't using ARC, you'll be leaking two strings, too. — bbum
– bbum, Commented Apr 24, 2012 at 19:29
Thanks for the tip, I am quite new and I just realized that. I am using ARC however. — StarvingPilot
– StarvingPilot, Commented Apr 24, 2012 at 19:34
No worries; Objective-C, iOS, Cocoa, and all the frameworks in between are very much built on a whole slew of common patterns. If you learn those patterns and follow them, it'll make things a whole lot simpler! — bbum
– bbum, Commented Apr 24, 2012 at 19:56

anon · Accepted Answer · 2012-04-24 19:20:42Z

2

You are changing the properties of the same radiostations object and adding it over and over again to the array. You need to create a new radiostations object for each row from your sqlite database and add this:

while (...) {
    // fetch data as before

    radiostations *record = [[radiostations alloc] init];
    [record setCity: cityField];
    [record setFormat: formatField];
    [amStationInfo addObject: record];
    [record release];
}

If you are using ARC you need to remove the line [record release];, otherwise it is necessary to avoid leaking those objects.

answered Apr 24, 2012 at 19:20

anon

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2 Comments

StarvingPilot Over a year ago

I am using ARC and therefore I am not releasing amStationClass

StarvingPilot Over a year ago

It works now, it turns out, I needed to allocate *record inside the while statement and not outside and I added the object into the Array after i set the strings... Thanks!

meronix · Accepted Answer · 2012-04-24 19:13:22Z

1

where did you allocate/init your mutablearray? something like:

NSMutableArray* amStationInfo = [[NSMutableArray alloc] init];

you need to allocate it once, before to add objects in it

answered Apr 24, 2012 at 19:13

meronix

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3 Comments

StarvingPilot Over a year ago

I forgot to allocate it, and even though I did, it still does not populate

meronix Over a year ago

i confess i read your question in hurry, when i noticed that error, but probably other are in... what about Sven answer?

StarvingPilot Over a year ago

Sven's answer worked. I changed two things, I allocated the instance inside the while loop and added in into the array after I set the strings.

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