How to get notified of UITableViewCell move start and end?

Question

I have a UITableView in my iOS app that gets refreshed periodically. The user is also able to move the tableview rows at all times (the tableview is always in editing mode).

I want to stop the refresh timer when the user starts dragging a row and start it again when the row is dropped.

The last part should be easy with moveRowAtIndexPath, but how to get notified about drag start?

Answer 1

Your UITableViewDelegate will receive the following notifications in response to reordering actions:

- (void)tableView:(UITableView *)tableView willBeginReorderingRowAtIndexPath:(NSIndexPath *)indexPath; - (void)tableView:(UITableView *)tableView didEndReorderingRowAtIndexPath:(NSIndexPath *)indexPath; - (void)tableView:(UITableView *)tableView didCancelReorderingRowAtIndexPath:(NSIndexPath *)indexPath; 

Answer 2

I ran into the same problem some time ago and didn't find a solution. While I started this answer with an explanation why it can't be done, I actually found out how it can be done! :-)

In short: You have to create a custom subclass of UITableViewCell. Override layoutSubviews to attach a UILongPressGestureRecognizer to UITableViewCellReorderControl. Define a protocol and use a delegate to inform whoever you want to about the dragging state.

CustomTableViewCell.h:

#import <UIKit/UIKit.h>  @protocol CustomTableViewCellDelegate;  @interface CustomTableViewCell : UITableViewCell { }  @property (nonatomic, assign) id <CustomTableViewCellDelegate> delegate;  @end  @protocol CustomTableViewCellDelegate - (void)CustomTableViewCell:(CustomTableViewCell *)cell isDragging:(BOOL)value; @end 

CustomTableViewCell.m:

#import "CustomTableViewCell.h"  @implementation CustomTableViewCell  @synthesize delegate = _delegate;  - (void)handleGesture:(UIGestureRecognizer *)gestureRecognizer {     if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {         [_delegate CustomTableViewCell:self isDragging:YES];    // Dragging started     } else if (gestureRecognizer.state == UIGestureRecognizerStateEnded) {         [_delegate CustomTableViewCell:self isDragging:NO];     // Dragging ended     } }  - (void)layoutSubviews {     [super layoutSubviews];      for (UIView *view in self.subviews) {         if ([NSStringFromClass ([view class]) rangeOfString:@"ReorderControl"].location != NSNotFound) {    // UITableViewCellReorderControl             if (view.gestureRecognizers.count == 0) {                 UILongPressGestureRecognizer *gesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleGesture:)];                 gesture.cancelsTouchesInView    = NO;                 gesture.minimumPressDuration    = 0.150;                 [view addGestureRecognizer:gesture];             }         }     } }  @end 

Be aware that while this code doesn't use any private APIs it still might stop working if Apple changes its internal implementation (i.e. by changing the classname of UITableViewCellReorderControl).