iOS: button in UITableViewCell class to call method on main UIViewController - iphone

Question

I have a UITableView on my MainViewController which has custom UITableCells defined in a CustomCell class. I need an UIButton, which is in my CustomCell class, to call a method in MainViewController. I cannot create a new instance of MainViewController because the method uses some variables which would all be in the default state if I created a new instance. What do I do??
This is my code:
MainViewController.m (this is the method I want called):
-(void)updateLabels{
double totalValue=0, personValue=0;
[self returnTickArray];
for(NSInteger i = 0; i < n; i++) {
totalValue += ([[[self returnPricesArray] objectAtIndex:i] doubleValue] * [[[self returnQtyArray] objectAtIndex:i]doubleValue]);
if([[[self returnPeopleArray] objectAtIndex:i]doubleValue]>0) personValue += ([[[self returnPricesArray] objectAtIndex:i] doubleValue] * [[[self returnQtyArray] objectAtIndex:i]doubleValue]/ [[[self returnPeopleArray] objectAtIndex:i]doubleValue] * [[[self returnTickArray] objectAtIndex:i]doubleValue]);
}
_totalValue.text = [NSString stringWithFormat:#"$ %.02lf", totalValue];
_tip.text= [NSString stringWithFormat:#"$ %.02lf", totalValue*(([_tipPercentage.text doubleValue]/100))];
_addedValue.text= [NSString stringWithFormat:#"$ %.02lf",([[_tip.text substringFromIndex:2] doubleValue]+totalValue) ];
_perPerson.text=[NSString stringWithFormat:#"$ %.02lf", personValue];
}
This is the method in CustomCell.m which gets called when I press the button:
- (IBAction)tick:(UIButton *)sender {
if ([sender isSelected]) {
[sender setImage:[UIImage imageNamed:#"off"] forState:UIControlStateNormal];
[sender setSelected:NO];
_isTicked = [NSNumber numberWithInt:0];
}
else {
[sender setImage:[UIImage imageNamed:#"on"] forState:UIControlStateSelected];
[sender setSelected:YES];
_isTicked = [NSNumber numberWithInt:1];
}
}

Answer 1

you can assign a method from your controller to a button from UITableView in your - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath method
[cell.yourButton addTarget:self action:#selector(updateLabels) forControlEvents:UIControlEventTouchUpInside];
(just don't forget to add IBOutlet of your button to your custom cell class)

Answer 2

Handling changes, actions, or user interaction in other views is the essential use case of delegates. The best practice is to have the MainViewController be the delegate of the CustomCell, and then as events happen in the cell (i.e., tick is called), it calls certain methods on its delegate to notify it and the delegate then calls updateLabels.
Other options for keeping values/state in sync between views are:
Core Data - best used for data
Key-Value Observation - best used for data
NSNotifications sent through NSNotificationCenter - best used for actions

Answer 3

interesting :)
You need to use [UIApplication sharedApplication] singleton to process this.
Here are few steps:
Create object of MainViewController In you AppDelegate class:
in AppDelegate.h import MainViewController.h
#interface AppDelegate
{
MainViewController *mvc;
}
#property (strong) MainViewController *mvc;
in MainViewController.m
#implementation AppDelegate
#synthesize mvc =_mvc
Now come to your CustomCell.m
- (IBAction)tick:(UIButton *)sender {
[[(AppDelegate *)[[UIApplication sharedApplication] delegate] hvc] tick:sender];
}
Here you are seeing a method is called- tick_fromCell:. Now you have to define this method in your MainViewController class' .h ans .m files.
in MainViewController.h
-(void)tick:(id)sender;
and in MainViewController.m
-(void)tick:(id)sender {
NSLog("Clicking from my CustomCell :)");// Here you will put updateLabels method
[self updateLabels];
}