You can easily grab the exact offset of the table view by looking at its `contentOffset` property. For the vertical scroll, look at:

    tableView.contentOffset.y;



The accepted solution only works if you know the size of all table view items. With auto sizing/estimated size that is not always true.

One alternative is to save the first visible item and scroll to it.

You can get the first visible item indexPath with:

    savedIndex = tableView.indexPathsForVisibleRows?.first


Then scroll to it by doing:

    tableView.scrollToRowAtIndexPath(savedIndex, atScrollPosition: .Top, animated: false)

Make sure you can load in viewWillAppear and not viewDidLoad (tested iOS 9). ViewWillAppear is when view has finished layout - there is differences in the outcome.

    -(void) viewWillAppear:(BOOL)animated {
        NSUserDefaults *lightData = [NSUserDefaults standardUserDefaults];
        [self.tableView setContentOffset:CGPointMake(0, [lightData floatForKey:@&quot;yValue&quot;])];
    }
    
    -(void) viewWillDisappear:(BOOL)animated {
        NSUserDefaults *lightData = [NSUserDefaults standardUserDefaults];
        [lightData setFloat:self.tableView.contentOffset.y forKey:@&quot;yValue&quot;];
        [lightData synchronize];
    }

Is it possible to call a function from one `Module` to another?

I have the following code:

    Sub MAIN()
        Call IDLE
    End Sub

 - `MAIN` is located in `Module1`
 - `IDLE` is located in `Module2` and defined as: `Sub IDLE()`

Call a Subroutine from a different Module in VBA

I am curious as to how F# performance compares to C++ performance?  I asked a similar question with regards to Java, and the impression I got was that Java is not suitable for heavy numbercrunching.

I have read that F# is supposed to be more scalable and more performant, but how is this real-world performance compares to C++?  specific questions about current implementation are:

 - How well does it do floating-point? 
 - Does it allow vector instructions
 - how friendly is it towards optimizing
   compilers?
 - How big a memory foot print does it have?  Does it allow fine-grained  control over memory locality? 
 - does it have capacity for distributed
   memory processors, for example Cray?
 - **what features does it have that may be of interest to computational science where heavy number processing is involved?**
 - Are there actual scientific computing
   implementations that use it?

Thanks

F# performance in scientific computing

Is there any way to find out which `UITableViewCell` is at the top of the scroll window?  

I&#39;d like to get the current scroll position so that I can save it when the app exits.  When the app gets started I want to scroll to the position it was at when it last exited.


How can I get the UITableView scroll position so I can save it?

<p>Is there any way to find out which <code>UITableViewCell</code> is at the top of the scroll window?</p>
<p>I'd like to get the current scroll position so that I can save it when the app exits.  When the app gets started I want to scroll to the position it was at when it last exited.</p>


I&#39;ve got a custom view inside of a `UIBarButtonItem`, set by calling `-initWithCustomView`.
My bar button item renders fine, but when I tap it, it doesn&#39;t invoke the action on my target object.

Here&#39;s my code:

    UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@&quot;someImage.png&quot;]];
    UIBarButtonItem *bbItem = [[UIBarButtonItem alloc] initWithCustomView:imageView];
    self.navigationItem.leftBarButtonItem = bbItem;
    [imageView release];
    [bbItem setTarget:self];
    [bbItem setAction:@selector(deselectAll)];


UIBarButtonItem: target-action not working?

Am I correct in thinking that to change the checkmark for &quot;on&quot; to &quot;off&quot;, I must change the `CellAccessoryType` between `none` and `checkmark` on the `didSelectRowAtIndexPath`?

Because I have done this but I have noticed the behaviour is not perfectly identical to like the checkmark cells on the auto lock settings on the iphone.

Or is there some other way checkmarks are meant to be handled?

UITableViewCell checkmark change on select

Is it possible to check inside ViewController class that it is presented as modal view controller?

Is it possible to determine whether ViewController is presented as Modal?

When I push a view after a user has selected a UITableView row, the row gets a blue highlight, and then the new view appears. That&#39;s fine. But when I go &#39;back&#39; the row is still highlighted in blue. Here&#39;s my didSelectRowAtIndexPath code.

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    {
    	SettingsViewController *controller = [[SettingsViewController alloc] initWithNibName:@&quot;SettingsView&quot; bundle:nil];
    	[[self navigationController] pushViewController:controller animated:YES];
    	[controller release], controller = nil;	
    }

What am I doing wrong?

Selected UItableViewCell staying blue when selected

I want to have a nice little icon that, when clicked will clear the text in the &amp;lt;INPUT&amp;gt; box.

This is to save space rather than having a clear link outside of the input box.

My CSS skills are weak...   Here is a &lt;strike&gt;screenshot&lt;/strike&gt; photo of how the iPhone looks.

&lt;img src=&quot;http://imgur.com/vOJFX.jpg&quot; alt=&quot;&quot;/&gt;

How do I put a clear button inside my HTML text input box like the iPhone does?

I want to search a specific string in the array of strings in objective c. Can somebody help me in this regard?

String search in string array in objective c

I would like to have my `UIActivityIndicatorView` be colored a custom color.  Is there any way to set this property?

Custom color my UIActivityIndicatorView

Is there a way to reduce the space between two sections of a UITableView? There are about 15 pixels between every single section I have. I did already try to return 0 for `-tableView:heightForFooterInSection:` and `-tableView:heightForHeaderInSection:` but that doesn&#39;t change anything.

Any suggestions?

Reducing the space between sections of the UITableView

I&#39;m working on a iPhone app which has a pretty large UITableView with data taken from the web, so I&#39;m trying to optimize its creation and usage.


I found out that `dequeueReusableCellWithIdentifier` is pretty useful, but after seeing many source codes using this, I&#39;m wondering if the usage I make of this function is the good one.

Here is what people usually do:

    UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:@&quot;Cell&quot;];
   
    if (cell == nil) {
      cell = [[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:@&quot;Cell&quot;];
    
    // Add elements to the cell
    return cell;

And here is the way I did it:

    // The cell row
    NSString identifier = [NSString stringWithFormat:@&quot;Cell %d&quot;, indexPath.row]; 
    
    UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:identifier];

    if (cell != nil)
      return cell;

    cell = [[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:identifier];
    // Add elements to the cell
    return cell;

The difference is that people use the same identifier for every cell, so dequeuing one only avoids to alloc a new one.

For me, the point of queuing was to give each cell a unique identifier, so when the app asks for a cell it already displayed, neither allocation nor element adding have to be done.

&lt;i&gt;In fine&lt;/i&gt; I don&#39;t know which is best, the &quot;common&quot; method ceils the table&#39;s memory usage to the exact number of cells it display, whilst the method I use seems to favour speed as it keeps all calculated cells, but can cause large memory consumption (unless there&#39;s an inner limit to the queue).

Am I wrong to use it this way? Or is it just up to the developer, depending on his needs?

iPhone - dequeueReusableCellWithIdentifier usage

On my iphone app, I have a UITableView in edit mode, where user is allowed only to reorder the rows no delete permission is given. 

So is there any way where I can hide &quot;-&quot; red button from TableView. Please let me know. 

Thanks




Is there any way to hide &quot;-&quot; (Delete) button while editing UITableView

I have a `UITableViewController` where the user should be able to edit the items. In order to enable editing I use this :

    self.navigationItem.rightBarButtonItem = self.editButtonItem;

For everyone who does not know where self.editButtonItem comes from, it is predefined by the SDK.

So, now when I press on any item, this method is called :

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 

but as soon as I hit the edit button and while editing is active, this method does not seemed to be called.

Any idea what I missing ? 

This is the rest of the code that is related to editing :

    // Override to support conditional editing of the table view.
    - (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath 
    {
    	// Return NO if you do not want the specified item to be editable.
    	return YES;
    }
    
    - (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath 
    {
    	return UITableViewCellEditingStyleNone;
    }
    
    
    - (BOOL)tableView:(UITableView *)tableView shouldIndentWhileEditingRowAtIndexPath:(NSIndexPath *)indexPath 
    {
    	return NO;
    }


Thanks for the help.

mcb



When editing, `UITableView` does not call didSelectRowAtIndexPath ??

I have a `UIScrollView` which contains many `UIImageView`s, UILabels, etc... the labels are much longer that the `UIScrollView`, but when I run the app, I cannot click and scroll down...

Why might this be?

Thanks

UIScrollView not scrolling

Is there a way to make a `UIScrollView` auto-adjust to the height (or width) of the content it&#39;s scrolling?

Something like:

    [scrollView setContentSize:(CGSizeMake(320, content.height))];

How do I auto size a UIScrollView to fit its content

I&#39;m writing an app that uses `UITabBar` for parts of the navigation. I&#39;m also using `UIScrollView` for presenting more information than what the screen can typically handle. Because of this, I&#39;m needing to set the scroll view to take into account the height of the `UITabBar` so that all of the information is displayed.

Is there a way to calculate the `height` of the `UITabBar`?


calculating height of UITabBar

What is the use of the `contentOffset` property in `UIScrollView`?

What does contentOffset do in a UIScrollView?

Note: The [answer given here][1] doesn&#39;t work for me.

I have a UIScrollView (not a table view, just a custom thing), and when the user takes certain actions, I want to kill any scrolling (dragging or deceleration) inside the view. I&#39;ve tried doing e.g. this:

    [scrollView scrollRectToVisible:CGRectInset([scrollView bounds], 10, 10) animated:NO];

on the theory that, given a rect that&#39;s already known visible, the scrolling will just stop where it is, but it turns out that this doesn&#39;t have any effect-- apparently the scroll view sees that the given rect is in bounds and takes no action. I **can** get the scroll to stop, if I give a rect that is definitely **outside** the currently-visible bounds, but inside the contentSize of the view. This seems to halt the view as expected... but also causes it to jump to some other location. I could probably do a little playing around at the margins to get this to work reasonably OK, but does anyone know of a clean way to halt a scroll view that&#39;s doing its thing?

Thanks.


  [1]: https://stackoverflow.com/questions/986392/programmatically-force-a-uiscrollview-to-stop-scrolling-for-sharing-a-table-view

Content Type	Original Author	Original Content on Stackoverflow
Question	progrmr	View Question on Stackoverflow
Solution 1 - Iphone	Ben Gottlieb	View Answer on Stackoverflow
Solution 2 - Iphone	Heinrisch	View Answer on Stackoverflow
Solution 3 - Iphone	coolcool1994	View Answer on Stackoverflow

How can I get the UITableView scroll position so I can save it?

Iphone Problem Overview

Iphone Solutions

Solution 1 - Iphone

Solution 2 - Iphone

Solution 3 - Iphone

F# performance in scientific computing

Call a Subroutine from a different Module in VBA

Attributions