UIScrollView inside UITableViewCell touch detect

Question

I have a tableview with 8 custom cells. in the 8th cell I added a scrollView with paging enabled so I can show page 1 and page 2 (or 3, 4... 10) without have a very high cell.

The problem is with the scrollView I can't use didSelectRowAtIndexPath because the cell is behind the scrollView so I'm trying to detect scrollView tap (not swipe).

I played with touchesBegan and touchesEnded but they are never called (I know touches work with UIView only, but maybe.....)

Any help is very appreciated.

Thanks, Max

Answer 1

There is a trick Apple recommends to use in this case, in theirs WWDC 2014 session "Advanced scrollviews" (See Demo starting from 8:10):

[cell.contentView addSubview:_scrollView];
[_scrollView setUserInteractionEnabled:NO];
[cell.contentView addGestureRecognizer:_scrollView.panGestureRecognizer];

That's all what needs to be done, no need to override touchesBegan:, touchesMoved: and others.

---

I used solution based on overriding of touchesBegan:, touchesMoved:, touchesEnded: and touchesCancelled: previously, but sometimes it caused a weird behaviour: when select a certain cell, method -tableView:didSelectRowAtIndexPath: was called for cell with different indexPath.

Solution from Apple has no side effects so far and looks more elegant.

Answer 2

There is also an elegant resolution:

Create a SubClass from UIScrollView and override the following methods

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [[self superview]touchesBegan:touches withEvent:event];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    [[self superview]touchesMoved:touches withEvent:event];
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
    [[self superview]touchesCancelled:touches withEvent:event];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    [[self superview]touchesEnded:touches withEvent:event];
}

Passing every touch to the superview of the scroll view and then the didSelectRowAtIndexPath will be called.

Answer 3

Solved subclassing both uitableviewcell and uiscrollview.

It worked for my needs. Hope it can help.

Max

---

myScrollView.h

#import <UIKit/UIKit.h>
@interface myScrollView : UIScrollView {
}

@end

myScrollView.m

#import "myScrollView.h"
@implementation myScrollView


- (id)initWithFrame:(CGRect)frame {

    return [super initWithFrame:frame];
}

- (void) touchesEnded: (NSSet *) touches withEvent: (UIEvent *) event 
{   
    NSLog(@"touch scroll");
    // If not dragging, send event to next responder
    if (!self.dragging) 
        [self.nextResponder touchesEnded: touches withEvent:event]; 
    else
        [super touchesEnded: touches withEvent: event];
}

myCell.h

#import <UIKit/UIKit.h>


@interface myCell : UITableViewCell {

}

@end

myCell.m

#import "myCell.h"


@implementation myCell


- (id)initWithFrame:(CGRect)frame {

    return [super initWithFrame:frame];
}

- (void) touchesEnded: (NSSet *) touches withEvent: (UIEvent *) event 
{   
    NSLog(@"touch cell");
    // If not dragging, send event to next responder
    [super touchesEnded: touches withEvent: event];
}

RootViewController.h

#import <UIKit/UIKit.h>

@class myCell;
@class myScrollView;

@interface RootViewController : UITableViewController {

    myCell *cell;
    myScrollView *scrollView;
}

@end

RootViewController.m

#pragma mark -
#pragma mark Table view data source

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


// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return 3;
}


// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"Cell";

    // my custom cell
    cell = [[myCell alloc] init];
    if (cell == nil) {
        cell = [[[myCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    }


    // the custom scroll view
    scrollView = [[myScrollView alloc] initWithFrame:cell.frame];
    scrollView.contentSize = CGSizeMake(640, 40);
    [cell.contentView addSubview:scrollView];

    //something to add in scrollView
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 150, 20)];
    label.text = @"some text";
    [scrollView addSubview:label];

    // Configure the cell.

    return cell;
}