Question

how is possible to make an iphone tab that loads selected data from an array and changes based on user selection.

Answer 1

Alx,

A simple scenario would be to create a NIB-based UITableViewCell (there are plenty of tutorials out there for this) which has a label on it of some kind.

What you can do is then grab the contents of the label when the user selects the cell and store that into a mutable array which then gets stored into the NSUserDefaults.

You can then access the NSUserDefaults from another view and use it to populate a “Favorites” tab like you’ve been asking about.

A little bit of sample code to help (assuming the original data is in a UITableView like you said in a prior question). I’m writing this off the top of my head (un-tested code), so you’ll have to work out any bugs, but the idea is correct.

// in the .h file
#import <UIKit/UIKit.h>

@interface MyViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> {

    // set up a mutable array which allows editing of the array
    NSMutableArray *myFavoritesData;

}
// set up a retained property
@property (nonatomic, retain) NSMutableArray *myFavoritesData;

@end


// in the .m file
// synthesize the getters/setters for your array
@synthesize myFavoritesData;

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 
{
    // find cell that was just pressed
    UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];

    // get pointer for the label that we want to identify the cell by
    // the tag in this case is set to '5' in Interface Builder in the options for the label
    UILabel *someLabel;
    someLabel = (UILabel *)[cell viewWithTag:5];

    NSString *tmpFavorite = someLabel.text;

    // get the count of the current array and use that for the "new" row since the count
    // will always be 1 larger than the last object in the array (arrays start at 0, counts start at 1) 
    NSUInteger newRow = [self.myFavoritesData count];
    [self.myFavoritesData insertObject:tmpFavorite atIndex:newRow]; 

}

// save the mutable array into NSUserDefaults when the view is about to disappear
- (void) viewWillDisappear:(BOOL)animated
{

    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    [userDefaults setObject:self.myFavoritesData forKey:@"MyFavorites"]; 

    // synchronize the data now instead of waiting for the OS to synchronize it at some 
    // arbitrary time in the future
    [userDefaults synchronize];

}

Once you are in the new view controller, you can just read from the NSUserDefaults and populate the table from the array. For instance:

// favorites view controller
- (void)viewDidLoad {

    [super viewDidLoad];

    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    NSMutableArray *tmpArray = [[NSMutableArray alloc] init];
    tmpArray = [[userDefaults objectForKey:@"MyFavorites"] mutableCopy];

        if ([tmpArray count] == 0) {

            //
            // no favorites have ever been saved
            //


        } else {

            // load the favorites into some array you synthesized just like before
            self.tableFavoritesData = [[NSMutableArray alloc] init];
            self.tableFavoritesData = [[userDefaults objectForKey:@"MyFavorites"] mutableCopy];

            NSLog(@"favorites data is %d and %@", [self.tableFavoritesData count], self.tableFavoritesData);

}

[tmpArray release];
}

Then in your cellForRowAtIndexPath of the favorites view controller you just access each string in each index of the array (so, string for index 0 would go into row 0, string for index 1 would go into row 1, etc) and this is what would populate your favorites table!

Try that out.