Databases
StackOverflow2013
Postsdbo
POHow can you add a UIGestureRecognizer to a UIBarButtonItem as in the common undo/redo UIPopoverController scheme on iPad apps?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow can you add a UIGestureRecognizer to a UIBarButtonItem as in the common undo/redo UIPopoverController scheme on iPad apps?
    primarykey
    data
    text
    <p><strong>Problem</strong></p> <p>In my iPad app, I cannot attach a popover to a button bar item <em>only</em> after press-and-hold events. But this seems to be standard for undo/redo. How do other apps do this? </p> <p><strong>Background</strong></p> <p>I have an undo button (UIBarButtonSystemItemUndo) in the toolbar of my UIKit (iPad) app. When I press the undo button, it fires it's action which is undo:, and that executes correctly. </p> <p>However, the "standard UE convention" for undo/redo on iPad is that pressing undo executes an undo but <em>pressing and holding</em> the button reveals a popover controller where the user selected either "undo" or "redo" until the controller is dismissed.</p> <p>The normal way to attach a popover controller is with presentPopoverFromBarButtonItem:, and I can configure this easily enough. To get this to show only after press-and-hold we have to set a view to respond to "long press" gesture events as in this snippet:</p> <pre><code>UILongPressGestureRecognizer *longPressOnUndoGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPressOnUndoGesture:)]; //Broken because there is no customView in a UIBarButtonSystemItemUndo item [self.undoButtonItem.customView addGestureRecognizer:longPressOnUndoGesture]; [longPressOnUndoGesture release]; </code></pre> <p>With this, after a press-and-hold on the view the method handleLongPressOnUndoGesture: will get called, and within this method I will configure and display the popover for undo/redo. So far, so good.</p> <p>The problem with this is that there <em>is no view</em> to attach to. self.undoButtonItem is a UIButtonBarItem, not a view.</p> <p><strong>Possible solutions</strong></p> <p>1) [The ideal] <em>Attach the gesture recognizer to the button bar item</em>. It is possible to attach a gesture recognizer to a view, but UIButtonBarItem is not a view. It does have a property for .customView, but that property is nil when the buttonbaritem is a standard system type (in this case it is).</p> <p>2) <em>Use another view</em>. I could use the UIToolbar but that would require some weird hit-testing and be an all around hack, if even possible in the first place. There is no other alternative view to use that I can think of. </p> <p>3) <em>Use the customView property</em>. Standard types like UIBarButtonSystemItemUndo have no customView (it is nil). Setting the customView will erase the standard contents which it needs to have. This would amount to re-implementing all the look and function of UIBarButtonSystemItemUndo, again if even possible to do.</p> <p><strong>Question</strong></p> <p>How can I attach a gesture recognizer to this "button"? More specifically, how can I implement the standard press-and-hold-to-show-redo-popover in an iPad app?</p> <p>Ideas? Thank you very much, especially if someone actually has this working in their app (I'm thinking of you, omni) and wants to share...</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USPeter Hosey
    1. USSG.
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow can you add a UIGestureRecognizer to a UIBarButtonItem as in the common undo/redo UIPopoverController scheme on iPad apps?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POHow can you add a UIGestureRecognizer to a UIBarButtonItem as in the common undo/redo UIPopoverController scheme on iPad apps?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POHow can you add a UIGestureRecognizer to a UIBarButtonItem as in the common undo/redo UIPopoverController scheme on iPad apps?
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload