Question

I’m making my first app and I’m using XCode 4 with a Storyboard. Thanks to this place, lots of tutorials, Apple’s archives databases and a bit of me, I’m slowly getting the basics together. It’s an app populated from a plist. The plist is an array with dictionaries, the dictionarires containing stings with info about different red wines in Norway. First, the plist populates a TableView. I’m using NSSortDescritor to sort the TableView and added a button to the navigation bar for resorting if I want it displayed by another value. It looks like this:

RootTableViewController.h:

#import <UIKit/UIKit.h>

@interface RootTableViewController : UITableViewController <UIActionSheetDelegate> {
NSMutableArray *sortedObjects;
}

-(IBAction)sortButtonPressed:(id)sender;

@end

RootTableViewController.m:

#import "RootTableViewController.h"
#import "ObjectCell.h"
#import "DetailViewController.h"

@interface RootTableViewController ()

@end

@implementation RootTableViewController

- (IBAction)sortButtonPressed:(id)sender;

{
    UIActionSheet *sort = [[UIActionSheet alloc]
   //InitWithStyle etc for sheet
}

-(void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex 
{
 NSSortDescriptor *sortDesc;

if (buttonIndex == 0) {
        sortDesc = [[NSSortDescriptor alloc] initWithKey:@"Name" ascending:YES];
        [sortedWines sortUsingDescriptors:[NSArray arrayWithObject:sortDesc]];
        }
if (buttonIndex == 1) {
        sortDesc = [[NSSortDescriptor alloc] initWithKey:@"Country" ascending:YES];
        [sortedWines sortUsingDescriptors:[NSArray arrayWithObject:sortDesc]];
}
[self.tableView reloadData];
}

- (void)viewDidLoad
{
[super viewDidLoad];

NSString *myfile = [[NSBundle mainBundle]
                    pathForResource:@"Objects" ofType:@"plist"];

sortedObjects = [[NSMutableArray alloc]initWithContentsOfFile:myfile];

NSSortDescriptor * sortDesc = [[NSSortDescriptor alloc] initWithKey:@"Popularity" ascending:YES];
[sortedObjects sortUsingDescriptors:[NSArray arrayWithObject:sortDesc]];
[super viewDidLoad];
}

- (void)viewDidUnload
{
    [super viewDidUnload];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

#pragma mark - Table view data source

- (void)viewWillAppear:(BOOL)animated {
    [self.tableView deselectRowAtIndexPath:[self.tableView indexPathForSelectedRow] animated:YES];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [sortedObjects count];
}

//(I’m using a Custom Cell for the TableView)

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"objectCell";

    ObjectCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {

    cell = [[[ObjectCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    }


    cell.nameLabel.text = [[sortedObjects objectAtIndex:indexPath.row] valueForKey:@"Name"];
    cell.countryLabel.text = [[sortedObjects objectAtIndex:indexPath.row] valueForKey:@"Country"];
    return cell;
}

#pragma mark - Table view delegate
//Then the selected object is sent to the DetailViewController in this segue:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {


    if ([[segue identifier] isEqualToString:@"DetailSegue"]) {

        NSIndexPath *selectedRowIndex = [self.tableView indexPathForSelectedRow];
        DetailViewController *detailViewController = [segue destinationViewController];

        detailViewController.selectedObject = [sortedObjects objectAtIndex:selectedRowIndex.row];
    }
}



@end

Then the DetailViewController recieves the selected object to populate the Labels and ImageViews with the data from it.

DetailViewController.h:

#import <UIKit/UIKit.h>

@interface DetailViewController : UIViewController 

@property (nonatomic, strong) IBOutlet UILabel *districtLabel;
@property (nonatomic, strong) IBOutlet UILabel *countryLabel;
@property (nonatomic, strong) IBOutlet UIImageView *bottleImageView;

@property (nonatomic, strong) NSString *selectedObject;

@end

DetailViewController.m:

#import "WinesDetailViewController.h"

@interface WinesDetailViewController ()

@end

@implementation WinesDetailViewController

@synthesize districtLabel,countryLabel,bottleImageView;

@synthesize selectedObject;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
    // Custom initialization
    }
    return self;
}


- (void)viewDidAppear:(BOOL)animated
{
    self.title = [selectedObject valueForKey:@"Name"];
    [super viewDidAppear:animated];
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    districtLabel.text = [selectedObject valueForKey:@"District"];
    countryLabel.text = [selectedObject valueForKey:@"Country"];
    bottleImageView.image = [UIImage imageNamed:[selectedObject valueForKey:@"Image"]];

self.navigationController.navigationBar.translucent = YES;
self.wantsFullScreenLayout = YES;

//Then I’ve added recognizers for left and right swiping:

UISwipeGestureRecognizer *leftGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeDetectedLeft:)];
leftGesture.direction = UISwipeGestureRecognizerDirectionLeft;
[self.view addGestureRecognizer:leftGesture];

UISwipeGestureRecognizer *rightGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeDetectedRight:)];
rightGesture.direction = UISwipeGestureRecognizerDirectionRight;
[self.view addGestureRecognizer:rightGesture];


}

//And the voids to handle the swipes:

- (void)swipeDetectedRight:(UISwipeGestureRecognizer *)sender
{
//Access previous cell in TableView
}

- (void)swipeDetectedLeft:(UISwipeGestureRecognizer *)sender
{
//Access next cell in TableView
}


//Some more besic code for the view..

@end

As you can see, I’ve added UISwipeGestureRecognizers in the DetailViewController, because I want to reload it with data from the previous cell to when swiped to the right, and next cell when swiped to the left. Now I have no idea how to handle the voids for swipe detected, how can I reach selectedRowIndex from DetailView and swipe through cells? I’m new to programming, have been trying to figure this out for a long time now, so code examples would be great so the answer don’t lead to 100 new questions if you know what I mean. Thank you so much if you can help me.

Answer 1

One way to go about this is to pass the “sorted” datasource array to the DetailViewController and the indexpath through the “prepareForSegue” method.

RootTableViewController.h:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {


    if ([[segue identifier] isEqualToString:@"DetailSegue"]) {

        NSIndexPath *selectedRowIndex = [self.tableView indexPathForSelectedRow];
        DetailViewController *detailViewController = [segue destinationViewController];

        detailViewController.selectedObject = [sortedObjects objectAtIndex:selectedRowIndex.row];

        //added code
        detailViewController.detailsDataSource = [[NSArray alloc]initWithArray:sortedObjects];
        detailViewController.detailIndex = selectedRowIndex.row;
    }
}

Then you could reload the UI elements of the DetailViewController.
Here is the declaration of the new properties.

DetailViewController.h:

#import <UIKit/UIKit.h>

@interface DetailViewController : UIViewController 

@property (nonatomic, strong) IBOutlet UILabel *districtLabel;
@property (nonatomic, strong) IBOutlet UILabel *countryLabel;
@property (nonatomic, strong) IBOutlet UIImageView *bottleImageView;

@property (nonatomic, strong) NSString *selectedObject;

// added code
@property (strong, nonatomic) NSArray *detailsDataSource;
@property int detailIndex;
@end

Don’t forget to synthesize the new properties
@synthesize detailsDataSource,detailIndex;

//And the voids to handle the swipes:

- (void)swipeDetectedRight:(UISwipeGestureRecognizer *)sender
{
//Access previous cell in TableView
    if (detailIndex != 0) // This way it will not go negative
          detailIndex--;  

    districtLabel.text = [[detailsDataSource objectAtIndex: detailIndex] valueForKey:@"District"]];
    countryLabel.text =  [[detailsDataSource objectAtIndex: detailIndex]  valueForKey:@"Country"];
    bottleImageView.image = [UIImage imageNamed:[[detailsDataSource objectAtIndex: detailIndex] valueForKey:@"Image"]];
}

- (void)swipeDetectedLeft:(UISwipeGestureRecognizer *)sender
{
//Access next cell in TableView
    if (detailIndex != [detailsDataSource count]) // make sure that it does not go over the number of objects in the array.
    detailIndex++;  // you'll need to check bounds 

    districtLabel.text = [[detailsDataSource objectAtIndex: detailIndex] valueForKey:@"District"]];
    countryLabel.text =  [[detailsDataSource objectAtIndex: detailIndex]  valueForKey:@"Country"];
    bottleImageView.image = [UIImage imageNamed:[[detailsDataSource objectAtIndex: detailIndex] valueForKey:@"Image"]];
}


//Some more besic code for the view..

@end

Give this a try it might work for you. Otherwise, I think you might want to take a look at Scrollview and “paging.” iPhone/iPad users are used to this UI design, and you might be able to modify it to fit what you are doing.