objective-c - 在 View Controller 之间拖放(包含在同一个 View Controller 中)

Question

我有一个 View Controller ，它显示在 Split View的详细 View 中，它由一个 TableView 和一个 Core Plot 图表 View 组成，如下所示:

我希望能够将单个 TableViewCells 拖放到 Core Plot View 中。

执行此操作的最佳方法是什么，因为手势识别器只能绑定(bind)到一个 View ？

如何为拖放 Action 设置动画？

关于 View Controller 包含的附加问题

如果两者都包含在同一个 View Controller 容器中(如在 iOS 5 中)，我如何实现从一个 View Controller 到另一个 View Controller 的拖放操作。

谢谢!

Answer 1

这是我用来将行从 Split View左侧面板的表格 View 拖到右侧面板详细信息屏幕的一些代码。这似乎与您的问题相似，但不可否认不完全相同。无论如何，我个人通过长按触发拖放:

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
[self.tableView addGestureRecognizer:longPress];

然后我的处理程序执行以下操作:

- (IBAction)longPress:(UIGestureRecognizer *)sender
{
    if (sender.state == UIGestureRecognizerStateBegan)
    {        
        // figure out which item in the table was selected

        NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:[sender locationInView:self.tableView]];
        if (!indexPath)
        {
            _inDrag = NO;
            return;
        }

        _inDrag = YES;

        // get the text of the item to be dragged

        NSString *text = [NSString stringWithString:[[_objects objectAtIndex:indexPath.row] description]];

        // create item to be dragged, in this example, just a simple UILabel

        UIView *splitView = self.splitViewController.view;
        CGPoint point = [sender locationInView:splitView];
        UIFont *font = [UIFont systemFontOfSize:12];
        CGSize size = [text sizeWithFont:font];
        CGRect frame = CGRectMake(point.x - (size.width / 2.0), point.y - (size.height / 2.0), size.width, size.height);
        _draggedView = [[UILabel alloc] initWithFrame:frame];
        [_draggedView setFont:font];
        [_draggedView setText:text];
        [_draggedView setBackgroundColor:[UIColor clearColor]];

        // now add the item to the view

        [splitView addSubview:_draggedView];
    }
    else if (sender.state == UIGestureRecognizerStateChanged && _inDrag) 
    {
        // we dragged it, so let's update the coordinates of the dragged view

        UIView *splitView = self.splitViewController.view;
        CGPoint point = [sender locationInView:splitView];
        _draggedView.center = point;
    }
    else if (sender.state == UIGestureRecognizerStateEnded && _inDrag)
    {
        // we dropped, so remove it from the view

        [_draggedView removeFromSuperview];

        // and let's figure out where we dropped it

        UIView *detailView = self.detailViewController.view;
        CGPoint point = [sender locationInView:detailView];

        UIAlertView *alert;
        if (CGRectContainsPoint(detailView.bounds, point))
            alert = [[UIAlertView alloc] initWithTitle:@"dropped in details view" message:nil delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
        else
            alert = [[UIAlertView alloc] initWithTitle:@"dropped outside details view" message:nil delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
        [alert show];
    }
}