Re: GC memory leak - what is it?
jonat...@mugginsoft.com wrote: A recent post mentioned the concept of GC memory leakage. How is is this defined? Is it merely a failure to nil out a rooted reference? Yes. If you hold a reference to memory you don't need anymore, you have a leak. I've gotten into huge flamewars over this, but I'm convinced of its truth. Consider a Java Document Object Model tree. Every node holds a reference to its parent and all of its children. If you hold a reference to any node in the tree, you prevent the entire tree from being collected. If you can't be sure that some other code will nil out your references, then nil them out yourself. Rippit the Ogg Frog rip...@oggfrog.com http://www.oggfrog.com/ ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Wierd Crash Report
From your crash log: Code Type: PPC (Translated) Translated - does that mean it's running under Rosetta on Intel? It can happen that there are Rosetta bugs that don't occur on native PowerPC hardware. While that shouldn't ever be the case, we all know that programmers are only human. David Blanton wrote: I ask this here as I have seen questions on Crash Reports. This is is Universal Binary ... why is there any PPC involved as it is running on Intel Process: Convert it [817] Path:/Applications/Convert it.app/Contents/MacOS/Convert it Identifier: com.BriTonLeap.convertitmac Version: 1.42b (7309) Code Type: PPC (Translated) Parent Process: launchd [74] Mike Crawford rip...@oggfrog.com http://www.oggfrog.com/ ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Data-Driven Animation
I'm working on what is now a Mac OS X prototype, that I'll be porting to the iPhone once I have a better architecture in place. Please forgive me for being vague about the precise nature of my product. :-D I need to better understand how to architect a 2-D animation in my app. I'm happy to Read The Fine Manual if you can give me some pointers as to where to look. I have a data model that is represented in graphical form on the screen. The data model updates many times per second. Each time the data model updates, I'd like to update the screen. What I do now I'm certain isn't correct. Whenever the data model has changed, the view object that holds the graphical representation calls: [self setNeedsDisplay: YES]; In the drawRect method, I convert the data model into its graphical representation. I'd like the data model to update as fast as it can; sometimes there will be several updates to the data model in between screen refreshes. That would actually be OK, if I don't see some of the steps in between refreshes; I just want whatever I do see to be completely consistent. A problem I see is that when drawRect is called, the data model might be part-way through updating. So the screen would have an inconsistent graphic drawn on it. I think what might work better is to have two off-screen graphics buffers. One of them will be updated according to the model, then only when that buffer is complete, a pointer will be switched that makes it the current graphics buffer, that is used by drawRect. Having two graphics buffers would enable me to draw into one without fear of screwing up the on-screen image, while the other has a completely consistent image. The current buffer would be copied to the screen by whatever Cocoa uses instead of the old Classic CopyBits. I know that Quartz has built-in double buffering. Could that help me somehow? Thanks for any advice you can give me. Mike Crawford rip...@oggfrog.com http://www.oggfrog.com ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: EXC_BAD_ACCESS in a Core Data application
Eric Hermanson wrote:
3. Attempting to access or return a local variable that has not been
initialized (although you may get a segmentation fault instead of a
BAD_ACCESS, I can't remember). For example,
- (BOOL)someMethod
{
BOOL returnValue;
// code in the method that never sets the returnValue to anything
return returnValue; // this is bad.
}
That's not really the best example. If someMethod returns a BOOL, than
no matter what value happens to occupy the memory that returnValue is
placed into, it will always be taken as true or false. It might not do
the right thing, but won't be likely to cause a crash.
A better example of code that would cause a crash is to return either an
uninitialized pointer, or a pointer to a struct that is a local variable.
--
Rippit the Ogg Frog
rip...@oggfrog.com
http://www.oggfrog.com/
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Re: Listening to Eject command
Ed Wynne wrote: you want DA for DiskArbitration. DiskArbitration is unfortunately rather poorly documented. It will take some trial and error to figure out how to make it work for you. But there are some developer blogs that yield some insight... ... unfortunately the bookmarks I had for them are on my other Mac, some sixty miles from where I am now... ... but Google could be your friend. I'm afraid I can't just post my source. But what I suggest you do is create a very simple application that has an NSTextView in it, and when you get any kind of notifications from DiskArbitration, append a message to the text view. Then put some buttons in your window, such that pressing the buttons result in commands being sent to DiskArbitration to mount, dismount and eject a volume, whose BSD name you can either enter manually in an NSTextField, or you could capture the BSD names that DiskArbitration tells you about and populate a menu with them. Note that you can dismount a volume without ejecting it. If you do that then launch Disk Utility, you'll see the volume's BSD name in Disk Utility's list, but greyed out. The volume is still known to the system, but just doesn't have a mounted filesystem. If you make such a testbed application as I describe, eventually DiskArbitration's operation will become quite clear and even appear sensibly designed. It's not that it's so difficult, it's that it's just undocumented. Ever Faithful, Rippit the Ogg Frog rip...@oggfrog.com http://www.oggfrog.com/ ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Cocoa Document-Based App v. Windows MDI App
The prevalence of MDI interfaces on Windows is one of the primary reasons I stick with the Mac, both as a user and as a developer. That is, it's not just that I prefer to use the Mac-standard user interface myself, but I also don't want to have to subject my users to user interfaces that I wouldn't willingly use myself. I've been a software engineer for twenty-one years, the majority of those spent coding for the Mac. And I can tell you - and you can quote me - that just about the best way for a Mac product to achieve poor reviews in the trade press is to make it look and act just like a Windows program. Look up the Macintosh User Interface guidelines at http://developer.apple.com/ and send the link to your coworkers. Emphasize the importance of a native look and feel. -- Rippit the Ogg Frog rip...@oggfrog.com http://www.oggfrog.com/ ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Identifying NSTextViews
How can one identify which of several NSTextViews has a given piece of
text in it?
I have a window with six NSTextViews. I made the window's controller
the delegate for each of them - or rather for their NSText base class.
My delegate's -textDidChange method gets called whenever the user edits
any of the views, and I can get the text like this:
- (void) textDidChange: (NSNotification*) notification
{
NSString *text = [[notification object] string];
// But which view was it?
return;
}
If my text items were NSTextFields rather than NSTextViews, I could set
a tag for each of them and check the tag in -textDidChange. But
NSTextViews don't have tags. NSTextFields have tags because they
subclass NSControl, but NSTextView isn't a subclass of NSControl.
I need to use views and not fields so they can have scrollbars and allow
multiple lines of text.
One way I could do it would be to subclass NSTextView and implement -tag
and -setTag in my subclass. But that seems like a lot of trouble to go
to for what must be a very common problem. Surely there is a better way.
In the list archives I saw a mention of creating a separate outlet in
the controller for each NSTextView, with each view being connected to a
separate outlet. I think that would work fine for me but I don't quite
understand how to go about it - I haven't done much Cocoa programming
before.
My objective is just to capture the text from each view when the window
is dismissed, so there could be another way to do what I want without
using a delegate. It's not necessary for me to get called for every
character the user types.
Thanks!
--
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rip...@oggfrog.com
http://www.oggfrog.com/
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Re: Identifying NSTextViews
Graham Cox wrote:
On 29/07/2009, at 1:56 PM, Rippit the Ogg Frog wrote:
- (void) textDidChange: (NSNotification*) notification
{
NSString *text = [[notification object] string];
// But which view was it?
return;
}
[notification object] is it.
Thanks, but that doesn't solve my problem. Maybe I should be more clear:
My problem isn't getting a pointer to one of the NSTextViews. My
problem is figuring out which of those NSTextViews a given pointer
refers to.
I have the views arranged in three rows and two columns, for a total of six.
When my delegate's method gets called, what I need to know is which row
and column the text view is located in, that called the delegate.
If I could use tags, as with NSTextField, then I would set the tags to
be integers ranging from 1 to 6. I could then check the tag and copy
the text into the appropriate member variable in my window's controller.
But I can't use tags because they're views and not fields.
Just having the pointer doesn't help unless I can use that to find out
which of the six views it points to.
Thanks!
--
Rippit the Ogg Frog
rip...@oggfrog.com
http://www.oggfrog.com/
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Re: Identifying NSTextViews
Sorry I hadn't seen Andy Lees response before I sent my immediately previous post. I think his solution will do what I need. I'll try it out and let you know. -- Rippit the Ogg Frog rip...@oggfrog.com http://www.oggfrog.com/ ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Identifying NSTextViews
This worked perfectly, however the window delegate method I needed in my particular case was windowDidResignKey, because I'm not actually closing the window when the user dismisses it, but calling orderOut:. Also NSTextView's string method returns a pointer to its internal buffer, so one should copy it and use the copy. Thanks for all your help everyone. Andy Lee wrote: In the list archives I saw a mention of creating a separate outlet in the controller for each NSTextView, with each view being connected to a separate outlet. I think that would work fine for me but I don't quite understand how to go about it - I haven't done much Cocoa programming before. In the header of your window controller class, declare instance variables like this: IBOutlet NSTextView * textViewOne; IBOutlet NSTextView * textViewTwo; ... etc. ... Save the file and return to Interface Builder. The new outlets will show up and you'll be able to make connections from your window controller to the various text views. == NOTE: make sure to connect to the text views and not the scroll views that enclose them. My objective is just to capture the text from each view when the window is dismissed, so there could be another way to do what I want without using a delegate. It's not necessary for me to get called for every character the user types. Implement the window delegate method windowWillClose:. Your window controller is probably already the window's delegate, but if it isn't, make that connection in IB. Then in windowWillClose:, collect the data from your six text views using [textViewOne string], [textViewTwo string], etc. --Andy -- Rippit the Ogg Frog rip...@oggfrog.com http://www.oggfrog.com/ ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
