Retrieving Selection State from Button Created in UITableViewCell

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In this article, we’ll explore how to retrieve the selection state of a button created within a UITableViewCell. We’ll delve into the world of Objective-C and iOS development, exploring the complexities of dynamic cell creation and interaction with custom view controllers.

Understanding the Problem

The problem at hand involves creating a custom table view cell with a dynamically generated button. The button is created on a separate class than the main view controller, which is our main concern. Our goal is to retrieve an array containing the selection state of each button within each cell.

We’ll examine both approaches: using the IBAction method and utilizing a public NSNumber property.

Approach 1: Using IBAction Method

In this section, we’ll explore how to use the IBAction method to track the selection state of our dynamically generated buttons.

Understanding the IBAction Method

The IBAction method is used to handle events triggered by a user interaction with an object in Interface Builder. In our case, it’s used to detect when a button is selected or deselected.

- (IBAction)tick:(UIButton *)sender {
    // Code here...
}

In this example, we’re using the IBAction method to handle the tick: event triggered by the button selection.

Implementing the Solution

To implement our solution, we’ll follow these steps:

1. Create an outlet for the button in our custom cell class.
2. Use the IBAction method to track the selection state of the button.
3. Return an array containing the selection state of each button within each cell.

Here’s a sample implementation:

#import <UIKit/UIKit.h>

@interface CustomCell : UITableViewCell

@property (strong, nonatomic) IBOutlet UIButton *tickButton;

@end

@implementation CustomCell

- (IBAction)tick:(UIButton *)sender {
    if ([sender isSelected]) {
        [sender setImage:[UIImage imageNamed:@"off"] forState:UIControlStateNormal];
        [sender setSelected:NO];
    } else {
        [sender setImage:[UIImage imageNamed:@"on"] forState:UIControlStateSelected];
        [sender setSelected:YES];
    }
}

@end

However, there’s an issue with this approach. In the MainViewController, we’re trying to get the selection state of a specific button at index 1 in section 0 using NSIndexPath indexPathForItem:1 inSection:0. However, as noted in the question, this will always return the same index.

To fix this, we need to use the actual row number instead of a hardcoded value. We can do this by replacing indexPathForItem:1 inSection:0 with just i, which represents the current iteration.

-(NSMutableArray*) returnTickArray{
    NSMutableArray *tickArray = [[NSMutableArray alloc] initWithCapacity:n];
    for (NSInteger i=0; i<n; i++){
        CustomCell *cell = (CustomCell *) [self.itemTable cellForRowAtIndexPath:indexPath];
        if ([cell.tickButton isSelected]){
            a=[NSNumber numberWithInt:1];
        }
        else {
            a=[NSNumber numberWithInt:0];
        };
        [tickArray addObject:a];
    }

    return tickArray;
}

However, we need to adjust our MainViewController code accordingly.

Approach 2: Using a Public NSNumber Property

In this section, we’ll explore an alternative approach using a public NSNumber property to track the selection state of each button.

Understanding the Concept

The idea is to create a public NSNumber property in our custom cell class that will be used to store the selection state. When a button is selected or deselected, it updates this property. The main view controller can then access and retrieve these values using its own code.

#import <UIKit/UIKit.h>

@interface CustomCell : UITableViewCell

@property (strong, nonatomic) IBOutlet UIButton *tickButton;
@property (nonatomic) NSNumber *selectionState;

@end

We’ll update the CustomCell implementation to track the selection state:

@implementation CustomCell

- (IBAction)tick:(UIButton *)sender {
    if ([sender isSelected]) {
        self.selectionState = @1; // 0 for off, 1 for on
        [sender setImage:[UIImage imageNamed:@"off"] forState:UIControlStateNormal];
        [sender setSelected:NO];
    } else {
        self.selectionState = @0;
        [sender setImage:[UIImage imageNamed:@"on"] forState:UIControlStateSelected];
        [sender setSelected:YES];
    }
}

@end

Now, in our MainViewController, we can access and retrieve the selection state of each button:

-(NSMutableArray*) returnTickArray{
    NSMutableArray *tickArray = [[NSMutableArray alloc] initWithCapacity:n];
    for (NSInteger i=0; i<n; i++){
        CustomCell *cell = (CustomCell *) [self.itemTable cellForRowAtIndexPath:indexPath];
        if ([cell.selectionState isEqual:@1]){
            a=[NSNumber numberWithInt:1];
        }
        else {
            a=[NSNumber numberWithInt:0];
        };
        [tickArray addObject:a];
    }

    return tickArray;
}

Conclusion

In this article, we’ve explored how to retrieve the selection state of buttons created within table view cells. We’ve examined two approaches using IBAction methods and public NSNumber properties.

However, there’s an important point: our code can be further improved for better performance. For instance, the main view controller needs to cache the cell objects before trying to get their selection states.

-(NSMutableArray*) returnTickArray{
    NSMutableArray *tickArray = [[NSMutableArray alloc] initWithCapacity:n];
    NSArray<CustomCell *> *cells = @[self.itemTable cellForRowAtIndexPath:indexPath ...];

    for (CustomCell *cell in cells){
        if ([cell.tickButton isSelected]){
            a=[NSNumber numberWithInt:1];
        }
        else {
            a=[NSNumber numberWithInt:0];
        };
        [tickArray addObject:a];
    }

    return tickArray;
}

We’ve demonstrated how to improve the performance of our code using a more efficient approach. We hope that this article has helped you navigate the complexities of dynamic table view cell creation and retrieval of button selection states in iOS development.

Last modified on 2023-07-11