How to sum contents of reusable Custom Cells for a Table View that acts as a Calculator

I built a table view, with Custom Table View Cells, where each cell has several UITextFields that allow the user to enter numbers that provide a calculation. The cell hast a subtotal UITextField that provides the result for that cell.

My problem is that I want to take the subtotal of that cell, and of each additional cell that the User uses, and provide a Total on a different UIView.

I do not know how to take the value of each subtotal for each cell, and furthermore, how can I know how many cells the user used, and all of this in order to provide the user with a TOTAL in a different view.

What would be the best way to achieve this?

Here is the Code.

I want to add new cells and be able to add them to the calculation. But each cell will hold different values that the user will provide.

Best!

#import <UIKit/UIKit.h>


@interface ProCalculator : UIViewController <UITableViewDelegate, UITableViewDataSource>      {

UITextField *totalField;
UITextField *differenceField;

UITextField *productField;
UITextField *price1Field;
UITextField *discount1P1Field;
UITextField *discount2P1Field;
UITextField *subtotal1Field;

UITextField *product2Field;
UITextField *price2Field;
UITextField *discount1P2Field;
UITextField *discount2P2Field;
UITextField *subtotal2Field;

}

@property (nonatomic, retain) IBOutlet UITextField *totalField;
@property (nonatomic, retain) IBOutlet UITextField *differenceField;

@property (nonatomic, retain) IBOutlet UITextField *productField;
@property (nonatomic, retain) IBOutlet UITextField *price1Field;
@property (nonatomic, retain) IBOutlet UITextField *discount1P1Field;
@property (nonatomic, retain) IBOutlet UITextField *discount2P1Field;
@property (nonatomic, retain) IBOutlet UITextField *subtotal1Field;

@property (nonatomic, retain) IBOutlet UITextField *product2Field;
@property (nonatomic, retain) IBOutlet UITextField *price2Field;
@property (nonatomic, retain) IBOutlet UITextField *discount1P2Field;
@property (nonatomic, retain) IBOutlet UITextField *discount2P2Field;
@property (nonatomic, retain) IBOutlet UITextField *subtotal2Field;


-(IBAction)calculateDiscounts:(id)s开发者_高级运维ender;
-(IBAction)removeKeyboard;


@end


#import "ProCalculator.h"
#import "ProductCell.h"


@implementation ProCalculator

@synthesize totalField, differenceField, productField, price1Field, discount1P1Field,     discount2P1Field, subtotal1Field;
@synthesize product2Field, price2Field, discount1P2Field, discount2P2Field, subtotal2Field;


-(IBAction)calculateDiscounts:(id)sender
{

//Calculate product 1 within first Cell

NSString *firstPrice = self.price1Field.text;
NSString *discount1P1 = self.discount1P1Field.text;
NSString *discount2P1 = self.discount2P1Field.text;

double subtotal1WithDiscount1;
double subtotal1WithDiscount2;
double firstPriceDouble = [firstPrice doubleValue];
double discount1P1Double = [discount1P1 doubleValue];
double discount2P1Double = [discount2P1 doubleValue];
double percentageDiscount1P1;
double percentageDiscount2P1;
double savings1P1;
double savings2P1;

percentageDiscount1P1 = discount1P1Double / 100; 
percentageDiscount2P1 = discount2P1Double / 100;
savings1P1 = firstPriceDouble * percentageDiscount1P1;
subtotal1WithDiscount1 = firstPriceDouble - savings1P1;
savings2P1 = subtotal1WithDiscount1 * percentageDiscount2P1;
subtotal1WithDiscount2 = subtotal1WithDiscount1 - savings2P1;

NSString *finalSubtotal1 = [[NSString alloc] initWithFormat:@"$ %.02f",   subtotal1WithDiscount2];

self.subtotal1Field.text = finalSubtotal1;


//Calculate product 2 within second Cell (Instead of Building more cells, I need to get information from User Input to create Cells and store information from them and add them to the calculation. 

NSString *secondPrice = self.price1Field.text;
NSString *discount1P2 = self.discount1P2Field.text;
NSString *discount2P2 = self.discount2P2Field.text;

double subtotal2WithDiscount1;
double subtotal2WithDiscount2;
double secondPriceDouble = [secondPrice doubleValue];
double discount1P2Double = [discount1P2 doubleValue];
double discount2P2Double = [discount2P2 doubleValue];
double percentageDiscount1P2;
double percentageDiscount2P2;
double savings1P2;
double savings2P2;

percentageDiscount1P2 = discount1P2Double / 100; 
percentageDiscount2P2 = discount2P2Double / 100;
savings1P2 = secondPriceDouble * percentageDiscount1P2;
subtotal2WithDiscount1 = secondPriceDouble - savings1P2;
savings2P2 = subtotal2WithDiscount1 * percentageDiscount2P2;
subtotal2WithDiscount2 = subtotal2WithDiscount1 - savings2P2;

NSString *finalSubtotal2 = [[NSString alloc] initWithFormat:@"$ %.02f", subtotal2WithDiscount2];

self.subtotal1Field.text = finalSubtotal2;



//Calculate Total

double totalAmount;
totalAmount = subtotal1WithDiscount2 + subtotal2WithDiscount2;
NSString *theTotal = [[NSString alloc] initWithFormat:@"$ %.02f", totalAmount];
self.totalField.text = theTotal;

//Calculate Money Saved

double moneySaved;
moneySaved = savings1P1 + savings2P1 + savings1P2 + savings2P2;
NSString *theMoneySaved = [[NSString alloc] initWithFormat:@"$ %.02f", moneySaved];
self.differenceField.text = theMoneySaved;


}

-(IBAction)removeKeyboard
{
[self.productField resignFirstResponder];
[self.price1Field resignFirstResponder];
[self.discount1P1Field resignFirstResponder];
[self.discount2P1Field resignFirstResponder];

}

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

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

- (void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];

// Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}

- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return 1;
}

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


ProductCell *cell = (ProductCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];

if (cell == nil) {

    NSArray *topLabel = [[NSBundle mainBundle] loadNibNamed:@"ProductTableViewCell" owner:self options:nil];

    for (id currentObject in topLabel) {

        if ([currentObject isKindOfClass:[ProductCell class]]) {
            cell = (ProductCell *) currentObject;
            break;

        }

    }

}



return cell;
}





@end

First of all, I assume you are using a custom UITableViewCell, which has a textfield as one of it's parameters.

I would suggest making an associated model with these cells, which has a parameter which stores the value of the textfield every time the user enters in new information. Something like:

@interface TableViewCellModel : NSObject {

  NSString * _valueOfTextfield;
}

@property (nonatomic, retain) NSString * valueOfTextfield;

@end

@implementation TableViewCellModel

@synthesize valueOfTextfield = _valueOfTextfield;

@end

Then, when the textfield is pressed, and the user enters in the information and resigns the textfield, update the associated model of the cell to store the value of the textfield.

When you want to show the TOTAL of the textfields in all the cells, just look at each of the cells corresponding models, and check if the valueOfTextfield property is nil or not.

One warning though, if each of the custom UITableViewCells has their own textfield, you could have some issues with performance, as well as your touch events in the cells. You may want to look into having a singleton class which handles the textfields separately, and each one of the custom cells having a reference to this singleton class.

EDIT: I have played with some code, and I think I have what you want now. You'll need a few files, and this gets a bit long. They will be in .h, then .m pairs.

@interface TableViewModel : NSObject {
  int _index;
  NSString * _textFieldValue;
}

@property (nonatomic, assign) int index;
@property (nonatomic, retain) NSString * textFieldValue;

@end

#import "TableViewModel.h"

@implementation TableViewModel

@synthesize index = _index;
@synthesize textFieldValue = _textFieldValue;

@end

Then,

#import <UIKit/UIKit.h>
@class TableViewModel;

@interface TableViewCell : UITableViewCell {
  IBOutlet UILabel * _label;
}

@property (nonatomic, retain) TableViewModel * tableViewModel;

- (IBAction)useTextField;

@end

#import "TableViewCell.h"
#import "TableViewModel.h"
#import "AppDelegate.h"

@implementation TableViewCell

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

- (void)setTableViewModel:(TableViewModel *)tableViewModel; {
  _label.text = [tableViewModel textFieldValue];
}

- (TableViewModel *)tableViewModel; {
  return nil;
}

- (IBAction)useTextField; {
  [[AppDelegate appDelegate] useTextFieldForIndex:[self.tableViewModel index]];
}

@end

and finally,

#import <UIKit/UIKit.h>
@class TableViewCell;

@interface ViewController : UIViewController <UITableViewDelegate, UITableViewDataSource, UITextFieldDelegate> {

  int _index;
  NSMutableArray * _items;
  IBOutlet TableViewCell * _cell;
  IBOutlet UITableView * _tableView;
  IBOutlet UITextField * _textField;
}

- (void)useTextFieldForIndex:(int)aIndex;

@end

#import "ViewController.h"
#import "TableViewModel.h"
#import "TableViewCell.h"

@implementation ViewController

- (void)dealloc; {
  [_items release];
  [super dealloc];
}

#pragma mark - View lifecycle

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad; {
  [super viewDidLoad];
  // This is an example of how to fill in the _items array with Models
  _items = [[NSMutableArray alloc] init];

  TableViewModel * model = [[TableViewModel alloc] init];
  model.textFieldValue = @"1";
  model.index = 0;

  [_items addObject:model];
  [model release];
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField; {
  TableViewModel * model = [_items objectAtIndex:_index];
  model.textFieldValue = [_textField.text retain];
  [_items replaceObjectAtIndex:_index withObject:model];
  [_tableView reloadData];
  [_textField resignFirstResponder];
  return YES;
}

// Customize the number of sections in the table view.
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView; {
  return 1;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath; {
  return 100;//This should be whatever the height of the cell is!
}

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

// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath; {

  NSString * cellIdentifier = @"TableViewCell";
  TableViewCell * cell = (TableViewCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];

  if (cell == nil) {

    [[NSBundle mainBundle] loadNibNamed:cellIdentifier owner:self options:nil]; // hooks up _cell for us
    cell = _cell;
  }

  cell.tableViewModel = ((TableViewModel *) [_items objectAtIndex:indexPath.row]);

  return cell;
}

- (void)useTextFieldForIndex:(int)aIndex; {
  _index = aIndex;
  [_textField becomeFirstResponder];
}

@end

I assume that you know how to hook up the nibs, but if you need any more help, just ask. Also, you'll need to add these 2 methods to the AppDelegate.

+ (AppDelegate *)appDelegate; {
  return (AppDelegate *)[[UIApplication sharedApplication] delegate];
}

- (void)useTextFieldForIndex:(int)aIndex; {
  [self.viewController useTextFieldForIndex:aIndex];
}

This will allow the AppDelegate to pass the actions to have the textfield actions in only one view controller. It also should help with performance. To give a bit of explanation, _items holds all of the models which are used in the tableview. (Side note: when you want the user to add a new cell, all you need to do is add a new model to this array.)

The action: - (IBAction)useTextField; is attached to a clear button, and when it is pushed, it tells the AppDelegate to tell the ViewController to bring up the keyboard, and once you are done with it, you update the model as the index of the cell that was pressed, and reload the tableview.

You can then customize the cells the way you want, and make sure that you match the models as well.

To add up the values in the Models, you need only use:

double sum = 0;

for(TableViewCellModel * model in _items){
  sum += [model.valueOfTextfield doubleValue];
}

Hope that helps!