iOS 8： - [UITableViewWrapperView textField]：发送到实例的无法识别的选择器

Question

Hello: I've been testing my app on iOS 6, 7, and now 8 (beta 5). My UITableView with custom UITableViewCell s is working fine on 6 and 7. However, on iOS 8, I'm getting a crash when I attempt to access a subview (text field) of a cell.

I am aware of the fact that there's another view in the cell's hierarchy in iOS 7. Strangely, it appears that this isn't the case in iOS 8. Here's the code I'm using:

    //Get the cell
    CustomCell *cell = nil;

    //NOTE: GradingTableViewCell > UITableViewCellScrollView (iOS 7+ ONLY) > UITableViewCellContentView > UIButton (sender)
    if (floor(NSFoundationVersionNumber) <= NSFoundationVersionNumber_iOS_6_1) {
        cell = (CustomCell *)sender.superview.superview;
    } else {
        cell = (CustomCell *)sender.superview.superview.superview;
    }

    //Get the cell's index path
    NSIndexPath *indexPath = [self.tableView indexPathForCell:cell];

    //etc.

    NSLog(@"%@", cell.textField); //<---Crashes here

So, as you can see, I'm accounting for the extra view in iOS 7. After adding some breakpoints and taking a closer look at the variables, I see that cell exists, but all the subviews it has in the interface file (which are linked up) - including textField - are nil . At the line specified, I'm receiving the following crash log:

-[UITableViewWrapperView textField]: unrecognized selector sent to instance 0x12c651430

I looked into this further, and I found this:

Changing the else statement to be identical to the preceding line gets rid of the crash, and the app works fine (using sender.superview.superview like in iOS 6).

This makes no sense to me. Did Apple revert the hierarchy of UITableViewCell s to that of iOS 6's, or am I missing something? Thanks!

Answer 1

I've encountered the same issue. Here's a more reliable method:

UITextField* textField = (UITextField*)sender;
NSIndexPath* indexPath = [self.tableView indexPathForRowAtPoint:[self.tableView convertPoint:textField.center fromView:textField.superview]];

This will work regardless of the underlying view hierarchy of UITableViewCell.

Answer 2

不同的iO版本具有不同的UITableView或UITableViewController ，作为一个简单的修复，您必须迭代superviews直到找到所需的视图类而不是依赖它作为第N个超级视图。

Answer 3

I also had the same issue on iOS8 with getting UITableViewCell via superview from a child view. This is what I came up with for both iOS7 and iOS8 support.

-(void)thumbTapped:(UITapGestureRecognizer*)recognizer {
    NSLog(@"Image inside a tableview cell is tapped.");

    UIImageView *mediaThumb = (UIImageView*)recognizer.view;
    UITableViewCell* cell;
    // get the index of container cell's row
    // bug with ios7 vs ios8 with superview level!! :(
    /*** For your situation the level of superview will depend on the design structure ***/
    // The rule of thumb is for ios7 it need an extra superview
    if (SYSTEM_VERSION_LESS_THAN(@"8.0")) { // iOS 7
        cell = (UITableViewCell*)mediaThumb.superview.superview.superview.superview;
    } else { // iOS 8
        cell = (UITableViewCell*)mediaThumb.superview.superview.superview;
    }
}

Just to clarify, in cellForRowAtIndexPath I assigned the tap gesture recognizer. The original design is very complex in Storyboard with many subviews, buttons.. etc.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MediaCell" forIndexPath:indexPath];
    .......    
    UIImageView *mediaImage = ............
    .....................................
    UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(thumbTapped:)];
    [mediaImage addGestureRecognizer:tapGestureRecognizer];

    return cell;
}