Implementing Drag and Drop Functionality Between Two UITableViews in iOS

Dragging UITableViewCell and Dropping it into Another UITableView

Overview

In this article, we will explore how to implement a drag-and-drop functionality between two UITableViews in iOS. We will use the UITableviewCell class to create a temporary cell that will hold the selected values from the first table view. This temporary cell will be removed from the data source of the first table view when the user drops it into another table view.

Understanding the Problem

The problem statement is as follows:

“I was able to get only partial output, main functionality of drag and drop was achieved but it was crashing some times and showing error as index out of bounds.”

This indicates that there are issues with the code that needs to be addressed in order to achieve a smooth drag-and-drop experience.

Solution Overview

To solve this problem, we will follow these steps:

Create a temporary cell to store the selected values from the first table view.
Remove the selected values from the data source of the first table view.
Add the temporary cell to the data source of the second table view when the user drops it into that view.
Reload the data in both table views after adding the temporary cell.

Step 1: Creating a Temporary Cell

First, we need to create a temporary cell to store the selected values from the first table view. This can be done by declaring a UITableviewCell instance variable in our ViewController’s .h file and initializing it in theViewController’s init method.

// ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@property (nonatomic, strong) UITableView *tableView1;
@property (nonatomic, strong) UITableView *tableView2;
@property (nonatomic, strong) UITableViewCell *tempCell;

@end

// ViewController.m

- (instancetype)init {
    self = [super init];
    if (self) {
        tempCell = [[UITableViewCell alloc] init];
        // You can configure the temporary cell as needed.
    }
    return self;
}

Step 2: Removing Selected Values from the Data Source

Next, we need to remove the selected values from the data source of the first table view. This can be done in the tableView:didSelectRowAtIndexPath: method.

// ViewController.m

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    // Get the selected row number.
    int pathNumber = indexPath.row;

    // Store the selected values in the temporary cell.
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    tempCell.accessoryType = UITableViewCellAccessoryCheckmark;
    if(tableView == tableView1) {
        [selectedCells addObject:[array objectAtIndex:pathNumber]];
        NSLog(@"indexpath-%d", indexPath.row);
        [arrayOfPaths addObject:indexPath];
        NSLog(@"----%@", selectedCells);
        NSLog(@"----======%@", arrayOfPaths);
    }
    else {
        [selectedCells1 addObject:[array1 objectAtIndex:pathNumber]];
        NSLog(@"indexpath-%d", indexPath.row);
        [arrayOfPaths1 addObject:indexPath];
        NSLog(@"====%@", selectedCells1);
        NSLog(@"----======]]]]]%@", arrayOfPaths1);
    }

    // Remove the selected values from the data source.
    if(tableView == tableView1) {
        [selectedCells removeObject:[array objectAtIndex:pathNumber]];
        [arrayOfPaths removeObject:indexPath];

        // Update the temporary cell's label with the removed value.
        UILabel *label = tempCell.view.subviews.firstObject;
        label.text = [NSString stringWithFormat:@"%d", pathNumber];
    }
    else {
        [selectedCells1 removeObject:[array1 objectAtIndex:pathNumber]];
        [arrayOfPaths1 removeObject:indexPath];

        // Update the temporary cell's label with the removed value.
        UILabel *label = tempCell.view.subviews.firstObject;
        label.text = [NSString stringWithFormat:@"%d", pathNumber];
    }

    [tempCell removeFromSuperview]; // Remove the temporary cell from its superview.
}

Step 3: Adding Temporary Cell to Data Source of Second Table View

Next, we need to add the temporary cell to the data source of the second table view when the user drops it into that view. This can be done in the touchesEnded:withEvent: method.

// ViewController.m

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    // Get the touch coordinates.
    CGPoint position = [self.view convertPoint:[touches anyObject] fromView:nil];

    // Check if the touch coordinates are within the bounds of the second table view.
    if(CGRectContainsPoint(tableView2.frame, position)) {
        NSLog(@"1-2");

        // Add the temporary cell to the data source of the second table view.
        [tableView2 insertRowsAtIndexPaths:arrayOfPaths withRowAnimation:UITableViewRowAnimationTop];
        [tempCell addSubview:UILabel *label = [[UILabel alloc] init]; label.text = @"Value"; label.frame = CGRectMake(0, 0, tempCell.bounds.size.width - 10, tempCell.bounds.size.height); tempCell.addSubview(label];

        // Reload the data in both table views.
        [tableView1 reloadData];
        [tableView2 reloadData];
    }
    else if(CGRectContainsPoint(tableView1.frame, position)) {
        NSLog(@"hi-2");

        // Add the temporary cell to the data source of the first table view.
        [tableView1 insertRowsAtIndexPaths:arrayOfPaths withRowAnimation:UITableViewRowAnimationTop];
        [tempCell addSubview:UILabel *label = [[UILabel alloc] init]; label.text = @"Value"; label.frame = CGRectMake(0, 0, tempCell.bounds.size.width - 10, tempCell.bounds.size.height); tempCell.addSubview(label];

        // Reload the data in both table views.
        [tableView1 reloadData];
        [tableView2 reloadData];
    }
}

Step 4: Removing Temporary Cell from Data Source

Finally, we need to remove the temporary cell from its superview after adding it to the data source of either table view.

// ViewController.m

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    // ...

    [self.view bringSubviewToFront:tempCell];

    // ...
}

Conclusion

In this article, we have implemented a drag-and-drop functionality between two UITableViews in iOS. We used the UITableviewCell class to create a temporary cell that would hold the selected values from the first table view. This temporary cell was removed from the data source of the first table view when the user dropped it into another table view.

We hope this article has been informative and helpful in understanding how to implement a drag-and-drop functionality between two UITableViews in iOS.

Last modified on 2024-11-10