What causes a UITableViewCell to be deallocated?
Hello.
I'm trying to track a crash in our app where we have a custom UITableView cell
that contains a UITextView because we need the ability to display and open
links that might be in the text we're displaying in the text view.
The problem is that somehow, the cell is deallocated and WebKit complains that
it's been unable to obtain the web lock from a thread other than the main
thread or the web thread when it's deallocated. I have reviewed the code and
checked all the reload… message we might send to the table view that could
cause the deallocation of its cells but all of those calls are executed from
the main thread using [[NSOperationQueue mainQueue] addOperationWithBlock:^{…}]
so I'm stumped. Are there any other situations where UITableView cells would be
deallocated? The view displays and the view isn't unloaded due to memory
warning or any other situation.
-Laurent.
--
Laurent Daudelin
AIM/iChat/Skype:LaurentDaudelin
http://www.nemesys-soft.com/
Logiciels Nemesys Software
laur...@nemesys-soft.com
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Re: What causes a UITableViewCell to be deallocated?
Think about it simply. A cell gets deallocated just like any other object -
when its retain count goes to zero. If you're looking for a cell getting
deallocated on a non-main thread, you're looking for a place release is being
called on a non-main thread. I would think you could just override the dealloc
method to help you track this situation in the debugger. Perhaps add an
NSAssert([NSThread isMainThread], @wups); in there.
Luke
On Jan 23, 2012, at 11:38 AM, Laurent Daudelin wrote:
Hello.
I'm trying to track a crash in our app where we have a custom UITableView
cell that contains a UITextView because we need the ability to display and
open links that might be in the text we're displaying in the text view.
The problem is that somehow, the cell is deallocated and WebKit complains
that it's been unable to obtain the web lock from a thread other than the
main thread or the web thread when it's deallocated. I have reviewed the code
and checked all the reload… message we might send to the table view that
could cause the deallocation of its cells but all of those calls are executed
from the main thread using [[NSOperationQueue mainQueue]
addOperationWithBlock:^{…}] so I'm stumped. Are there any other situations
where UITableView cells would be deallocated? The view displays and the view
isn't unloaded due to memory warning or any other situation.
-Laurent.
--
Laurent Daudelin
AIM/iChat/Skype:LaurentDaudelin
http://www.nemesys-soft.com/
Logiciels Nemesys Software
laur...@nemesys-soft.com
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Re: What causes a UITableViewCell to be deallocated?
It seems that the deallocation happens when a block is being deallocated. Is it
possible that a block ran on the main queue of an NSOperationQueue could be
deallocated in another thread?
-Laurent.
--
Laurent Daudelin
AIM/iChat/Skype:LaurentDaudelin
http://www.nemesys-soft.com/
Logiciels Nemesys Software
laur...@nemesys-soft.com
On Jan 23, 2012, at 13:49, Laurent Daudelin wrote:
Hello Luke.
Well, I already checked that. The cell is being deallocated from a secondary
thread but there is nothing in the thread that indicates what triggered it.
It looks like a performSelector:withObject:afterDelay: or something like it
but we don't have any of those in the table view controller that controls the
table view. Like I said in my original message, I've looked for any flavor of
UITableView reload… and the only calls we have are reloadData but they are
all executed on the main thread using [[NSOperationQueue] mainQueue]
addOperationWithBlock: so I'm stumped as to where this deallocation is
triggered. I've checked all the other running threads and I can't find any
code that you reload the table view which could cause its cells to be
deallocated.
-Laurent.
--
Laurent Daudelin
AIM/iChat/Skype:LaurentDaudelin
http://www.nemesys-soft.com/
Logiciels Nemesys Software
laur...@nemesys-soft.com
On Jan 23, 2012, at 13:38, Luke Hiesterman wrote:
Think about it simply. A cell gets deallocated just like any other object -
when its retain count goes to zero. If you're looking for a cell getting
deallocated on a non-main thread, you're looking for a place release is
being called on a non-main thread. I would think you could just override the
dealloc method to help you track this situation in the debugger. Perhaps add
an NSAssert([NSThread isMainThread], @wups); in there.
Luke
On Jan 23, 2012, at 11:38 AM, Laurent Daudelin wrote:
Hello.
I'm trying to track a crash in our app where we have a custom UITableView
cell that contains a UITextView because we need the ability to display and
open links that might be in the text we're displaying in the text view.
The problem is that somehow, the cell is deallocated and WebKit complains
that it's been unable to obtain the web lock from a thread other than the
main thread or the web thread when it's deallocated. I have reviewed the
code and checked all the reload… message we might send to the table view
that could cause the deallocation of its cells but all of those calls are
executed from the main thread using [[NSOperationQueue mainQueue]
addOperationWithBlock:^{…}] so I'm stumped. Are there any other situations
where UITableView cells would be deallocated? The view displays and the
view isn't unloaded due to memory warning or any other situation.
-Laurent.
--
Laurent Daudelin
AIM/iChat/Skype:LaurentDaudelin
http://www.nemesys-soft.com/
Logiciels Nemesys Software
laur...@nemesys-soft.com
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Re: What causes a UITableViewCell to be deallocated?
A UITableViewCell could be deallocated as soon as its row scrolls out of view.
UITableView will reuse cells if you specify a reuse identifier, but I don't
believe that the docs actually specify the number of cells that are reused.
I'm assuming that the web view is displayed when the user taps a link in the
UITextView. If so, when does the crash occur relative to the appearance of the
web view?
On Jan 23, 2012, at 11:38 AM, Laurent Daudelin wrote:
I'm trying to track a crash in our app where we have a custom UITableView
cell that contains a UITextView because we need the ability to display and
open links that might be in the text we're displaying in the text view.
The problem is that somehow, the cell is deallocated and WebKit complains
that it's been unable to obtain the web lock from a thread other than the
main thread or the web thread when it's deallocated. I have reviewed the code
and checked all the reload… message we might send to the table view that
could cause the deallocation of its cells but all of those calls are executed
from the main thread using [[NSOperationQueue mainQueue]
addOperationWithBlock:^{…}] so I'm stumped. Are there any other situations
where UITableView cells would be deallocated? The view displays and the view
isn't unloaded due to memory warning or any other situation.
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Re: What causes a UITableViewCell to be deallocated?
Steve,
There are no web views. Because we're using a UITextView, it loads the WebKit
behind the scene (I guess to support links that could appear in the text in the
UITextView) and when that UITextView is deallocated from another thread than
the main thread or the webkit thread, it raises an exception that crashes the
app. This happens only in iOS 4.3.5. I'm not sure if all my UITableView
operations are run on the main thread why when that block is deallocated, it
would be on a secondary thread. That seems to be the problem.
-Laurent.
--
Laurent Daudelin
AIM/iChat/Skype:LaurentDaudelin
http://www.nemesys-soft.com/
Logiciels Nemesys Software
laur...@nemesys-soft.com
On Jan 23, 2012, at 15:49, Steve Christensen wrote:
A UITableViewCell could be deallocated as soon as its row scrolls out of
view. UITableView will reuse cells if you specify a reuse identifier, but I
don't believe that the docs actually specify the number of cells that are
reused.
I'm assuming that the web view is displayed when the user taps a link in the
UITextView. If so, when does the crash occur relative to the appearance of
the web view?
On Jan 23, 2012, at 11:38 AM, Laurent Daudelin wrote:
I'm trying to track a crash in our app where we have a custom UITableView
cell that contains a UITextView because we need the ability to display and
open links that might be in the text we're displaying in the text view.
The problem is that somehow, the cell is deallocated and WebKit complains
that it's been unable to obtain the web lock from a thread other than the
main thread or the web thread when it's deallocated. I have reviewed the
code and checked all the reload… message we might send to the table view
that could cause the deallocation of its cells but all of those calls are
executed from the main thread using [[NSOperationQueue mainQueue]
addOperationWithBlock:^{…}] so I'm stumped. Are there any other situations
where UITableView cells would be deallocated? The view displays and the view
isn't unloaded due to memory warning or any other situation.
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