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thanatos · Apr 9, 2002, 04:58 PM

Hi!

I found the code att the bottom of this post somewhere in this forum. I made an interface with a textField, a textView and a button. It's an example on how to use threads.

When I write in the textField and press a OK button my text should appear in the textView 60 times without locking up the interface.

But all it does is crash all the time with this message:

<BLOCKQUOTE>code:<HR><pre>
2002-04-10 00:07:29.925 ThreadTest[1872] *** Assertion failure in -[NSMutableRLEArray objectAtIndex:effectiveRange:], String.subproj/NSAttributedString.m:923
2002-04-10 00:07:29.925 ThreadTest[1872] An uncaught exception was raised
2002-04-10 00:07:29.926 ThreadTest[1872] Access invalid attribute location 0 (length 0)
2002-04-10 00:07:29.926 ThreadTest[1872] *** Uncaught exception: <NSInternalInconsistencyException&gt ; Access invalid attribute location 0 (length 0)
[/code]

I'm quite a newbie to this Cocoa thing, so any help would be nice...

<BLOCKQUOTE>code:<HR><pre>
#import "myClass.h"

@implementation myClass

- (IBAction)OKBUTTON

id)sender;
{
[NSApplication detachDrawingThread: @selector (doSomething

toTarget:self withObject:[[input stringValue] retain]];
}

- (void)doSomething

NSString *)inputString
{
NSAutoreleasePool* pool;
NSRange range;
int length, i;

range.location = 0;
range.length = [inputString length];

for(i = 0;i < 60; i++)
{

pool = [[NSAutoreleasePool alloc] init];

[output replaceCharactersInRange:range withString:inputString];
range.location += length;
[NSThread sleepUntilDate:[NSDate dateWithTimeIntervalSinceNow:1]];

[pool release];

}
[inputString release];
}

@end
[/code]

Here's myClass.h:
<BLOCKQUOTE>code:<HR><pre>
#import <Cocoa/Cocoa.h>

@interface myClass : NSView
{
IBOutlet id input;
IBOutlet id output;
}
- (IBAction)OKBUTTON

id)sender;
- (void)doSomething

NSString *)inputString;

@end
[/code]

[ 04-09-2002: Message edited by: thanatos ]

Apocalypse · Apr 10, 2002, 02:42 PM

Well, I would wonder about the call to "replaceCharactersInRange:withString:" because I am not sure if it likes being told to replace a part of a string that does not exist (I am not sure, though, since I haven't used that in a while).

Also, this isn't the best application of multi-threading since it requires a thread other than the main thread to modify the display. It _should_ be fine but I have had kernel panics while doing that before (although it was an NSOpenGLView and I was explicitly calling "display" after making my modifications to data). Unless you are using this to experiment with threads it would be better to us an NSTimer.

Hope that helps,
Jeff.

bewebste · Apr 10, 2002, 03:01 PM

Your problem is that you are replacing characters in an invalid range. I assume that when you start out, your output view is empty, yes? Well, then when you try to replace the characters in the range {0, [inputString length]}, this range goes beyond the range of the characters in the text view, since there are zero characters. What you want to do is to set the range.length to 0 instead of [inputString length] initially. That way, you start out replacing the range {0, 0} and then increment the location each time so that the range is at the end of the text view.

One additional thing, since you are doing these changes from another thread, you might want to call [output display] after you insert the new characters each time. The view will not be automatically redrawn right away when you insert the new characters, but will instead be redrawn by the main thread the next time it goes through the event loop. This may result in the main thread trying to update at the same time you are inserting new characters, which could definitely lead to Bad Things�.

thanatos · Apr 11, 2002, 04:51 PM

Originally posted by bewebste:
Your problem is that you are replacing characters in an invalid range. I assume that when you start out, your output view is empty, yes? Well, then when you try to replace the characters in the range {0, [inputString length]}, this range goes beyond the range of the characters in the text view, since there are zero characters. What you want to do is to set the range.length to 0 instead of [inputString length] initially. That way, you start out replacing the range {0, 0} and then increment the location each time so that the range is at the end of the text view.

One additional thing, since you are doing these changes from another thread, you might want to call [output display] after you insert the new characters each time. The view will not be automatically redrawn right away when you insert the new characters, but will instead be redrawn by the main thread the next time it goes through the event loop. This may result in the main thread trying to update at the same time you are inserting new characters, which could definitely lead to Bad Things�.

I put some text in the textbox and changed the range.length to 0. It now works a bit better, it still crashes, but after a second. Before it crashed right away.

this is the error I get now:

<BLOCKQUOTE>code:<HR><pre>
2002-04-11 23:39:27.605 ThreadTest[2813] *** Assertion failure in -[NSMutableRLEArray objectAtIndex:effectiveRange:], String.subproj/NSAttributedString.m:923
2002-04-11 23:39:27.606 ThreadTest[2813] An uncaught exception was raised
2002-04-11 23:39:27.606 ThreadTest[2813] Access invalid attribute location -2021289070 (length 19)
2002-04-11 23:39:27.606 ThreadTest[2813] *** Uncaught exception: <NSInternalInconsistencyException&gt ; Access invalid attribute location -2021289070 (length 19)
[/code]

Maybe I have done something wrong, but my code looks like this now:

<BLOCKQUOTE>code:<HR><pre>
#import "myClass.h"

@implementation myClass

- (IBAction)OKBUTTON

id)sender;
{
[NSApplication detachDrawingThread: @selector (doSomething

toTarget:self withObject:[[input stringValue] retain]];
}

- (void)doSomething

NSString *)inputString
{
NSAutoreleasePool* pool;
NSRange range;
int length, i;

range.location = 0;
range.length = 0;

for(i = 0;i < 60; i++)
{
pool = [[NSAutoreleasePool alloc] init];

[output replaceCharactersInRange:range withString:inputString];
[output display];
range.location += length;

[NSThread sleepUntilDate:[NSDate dateWithTimeIntervalSinceNow:1]];
[pool release];

}
[inputString release];
}

@end

[/code]