Trying to create a Skat-Game, I encountered the following problem:
isBidding is a Boolean value indicationg, the program is in a certain state,
[desk selected] is a method calling returning the current selected player,
chatStrings consists of dictionaries, saving strings with the player, who typed, and what he typed
- (void)drawRect:(NSRect)rect{
NSMutableDictionary * attributes = [NSMutableDictionary dictionary];
[attributes setObject:[NSFont fontWithName:playerFont size:playerFontSize] forKey:NSFontAttributeName];
[attributes setObject:playerFontColor forKey:NSForegroundColorAttributeName];
[[NSString stringWithFormat:#"Player %i",[desk selected] + 1] drawInRect:playerStringRect withAttributes:attributes];
if (isBidding){
[attributes setObject:[NSFont fontWithName:chatFont size:chatFontSize] forKey:NSFontAttributeName];
[attributes setObject:chatFontColor forKey:NSForegroundColorAttributeName];
int i;
for (i = 0; i < [chatStrings count]; i++, yProgress -= 20){
if (isBidding)
[[NSString stringWithFormat:#"Player %i bids: %#",
[[[chatStrings objectAtIndex:i]valueForKey:#"Player"]intValue],
[[chatStrings objectAtIndex:i]valueForKey:#"String"]],
drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes];
else
[[NSString stringWithFormat:#"Player %i: %#",[[[chatStrings objectAtIndex:i] valueForKey:#"Player"]intValue],
[[chatStrings objectAtIndex:i]valueForKey:#"String"]]
drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes];
}
}
if (isBidding)
[[NSString stringWithFormat:#"Player %i bids: %#",[desk selected] + 1, displayString]
drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes];
else
[[NSString stringWithFormat:#"Player %i: %#",[desk selected] + 1, displayString]
drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes];
yProgress = chatFontBegin;
}
This is the part determining the string's content, the string is contributed by an [event characters] method.
-(void)displayChatString:(NSString *)string{
displayString = [displayString stringByAppendingString:string];
[self setNeedsDisplay:YES];
}
The problem if have is this:
when typing in more than two letters the view displays NSRectSet{{{471, 574},{500, 192}}}
and returns no more discription when I try to print it.
then I get an EXC_BAD_ACCESS message, though I have not released it (as far as I can see) I also created the string with alloc and init, so I cannot be in the autorelease pool.
I also tried to watch the process when it changes with the debugger, but I couldn't find any responsible code.
As you can see I am still a beginner in Cocoa (and programming in general), so I would be really happy if somebody would help me with this.
This code is buggy:
-(void)displayChatString:(NSString *)string{
displayString = [displayString stringByAppendingString:string];
[self setNeedsDisplay:YES];
}
stringByAppendingString: returns an autoreleased object. You need to retain or copy it if you want it to stick around (maybe by using a copying/retaining property like self.displayString = [displayString stringByAppendingString:string]; and the matching property declaration/synth.
So at the moment, you are assigning an object which will be deallocated, but you later access it giving the error.
I can't puzzle out your code but I can tell you something about the odd return.
NSRectSet is a private type inside the Foundation framework. You shouldn't ever see it. Its used internally IIRC to represent nested rectangles such as those of stacks of views.
You're either getting an odd memory problem that causes a string pointer to actually point at the NSRectSet or you've screwed up your method nesting and you're assigning the NSRectSet value to a string.
Related
I'm trying to do the following - I have an Array in which some strings are stored. These strings shall be used to call an NSArray. An example will clarify what I'm trying to do:
This is the working code that I'm trying to achieve ("briefing0" is of type NSArray):
NSString *path = [docsDir stringByAppendingPathComponent:[briefing0 objectAtIndex:indexPath.row]];
This is the "same" code that I'm trying to use:
int i = 0;
NSString *path = [docsDir stringByAppendingPathComponent:[(NSArray *)[NSString stringWithFormat:#"briefing%d", i] objectAtIndex:indexPath.row]];
Any ideas?
Thanks in advance!
Tom
Assuming that briefing0 is actually a property, then yes, this is possible (and not uncommon) in ObjC via KVC.
int i = 0;
NSString *prop = [NSString stringWithFormat:#"briefing%d", i];
NSArray *array = [self valueForKey:prop];
NSString *value = [array objectAtIndex:indexPath.row];
... etc. ...
-valueForKey: is the piece you're looking for. Note that this will throw an exception if you construct a key that does not exist, and so must be used with extreme care.
I need to see if an object that I have obtained from a CSV file with a unique identifier exists in my Core Data Database, and this is the code I deemed suitable for this task:
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity;
entity =
[NSEntityDescription entityForName:#"ICD9"
inManagedObjectContext:passedContext];
[fetchRequest setEntity:entity];
NSPredicate *pred = [NSPredicate predicateWithFormat:#"uniqueID like %#", uniqueIdentifier];
[fetchRequest setPredicate:pred];
NSError *err;
NSArray* icd9s = [passedContext executeFetchRequest:fetchRequest error:&err];
[fetchRequest release];
if ([icd9s count] > 0) {
for (int i = 0; i < [icd9s count]; i++) {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init];
NSString *name = [[icd9s objectAtIndex:i] valueForKey:#"uniqueID"];
if ([name caseInsensitiveCompare:uniqueIdentifier] == NSOrderedSame && name != nil)
{
[pool release];
return [icd9s objectAtIndex:i];
}
[pool release];
}
}
return nil;
After more thorough testing it appears that this code is responsible for a huge amount of leaking in the app I'm writing (it crashes on a 3GS before making it 20 percent through the 1459 items). I feel like this isn't the most efficient way to do this, any suggestions for a more memory efficient way? Thanks in advance!
Don't use the like operator in your request predicate. Use =. That should be much faster.
You can specify the case insensitivity of the search via the predicate, using the [c] modifier.
It's not necessary to create and destroy an NSAutoreleasePool on each iteration of your loop. In fact, it's probably not needed at all.
You don't need to do any of the checking inside the for() loop. You're duplicating the work of your predicate.
So I would change your code to be:
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
[fetchRequest setEntity:...];
[fetchRequest setPredicate:[NSPredicate predicateWithFormat:#"uniqueID =[c] %#", uniqueIdentifier]];
NSError *err = nil;
NSArray *icd9s = [passedContext executeFetchRequest:fetchRequest error:&err];
[fetchRequest release];
if (error == nil && [icd9s count] > 0) {
return [icd9s objectAtIndex:0]; //we know the uniqueID matches, because of the predicate
}
return nil;
Use the Leaks template in Instruments to hunt down the leak(s). Your current code may be just fine once you fix them. The leak(s) may even be somewhere other than code.
Other problems:
Using fast enumeration will make the loop over the array (1) faster and (2) much easier to read.
Don't send release to an autorelease pool. If you ever port the code to garbage-collected Cocoa, the pool will not do anything. Instead, send it drain; in retain-release Cocoa and in Cocoa Touch, this works the same as release, and in garbage-collected Cocoa, it pokes the garbage collector, which is the closest equivalent in GC-land to draining the pool.
Don't repeat yourself. You currently have two [pool release]; lines for one pool, which gets every experienced Cocoa and Cocoa Touch programmer really worried. Store the result of your tests upon the name in a Boolean variable, then drain the pool before the condition, then conditionally return the object.
Be careful with variable types. -[NSArray count] returns and -[NSArray objectAtIndex:] takes an NSUInteger, not an int. Try to keep all your types matching at all times. (Switching to fast enumeration will, of course, solve this instance of this problem in a different way.)
Don't hide releases. I almost accused you of leaking the fetch request, then noticed that you'd buried it in the middle of the code. Make your releases prominent so that you're less likely to accidentally add redundant (i.e., crash-inducing) ones.
I'm not sure what I'm doing wrong. I have a NSTextView and am registered as the delegate for its textStorage attribute. When I receive -textStorageDidProcessEditing:notification: I'm trying to apply attributes to ranges of characters within the text. It certainly does "something" to the characters, but not what I expect... they just disappear!
A heavily distilled code example. This should make sure the second character in the text field is always red:
-(void)textStorageDidProcessEditing:(NSNotification *)notification {
NSTextStorage *textStorage = [textView textStorage];
if ([[textStorage string] length] > 1) {
NSColor *color = [NSColor redColor];
NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:color, NSForegroundColorAttributeName, nil];
[textStorage setAttributes:attributes range:NSMakeRange(1, 1)];
}
}
Instead, as I type the sequence "abcdefg" I get "a", then when I hit "b" seemingly nothing happens, then when I hit "cdefg" typing occurs as normal, making the end result "acdefg"... the "b" is missing!
If I start hitting backspace I have to hit backspace 7 times, as if the "b" is actually there, but just not being drawn (cursor stalls as it deletes the "b", then on the next backspace deletes the "a" as expected).
If I apply attributes to some default text in the view using the same -setAttributes:range: method before the view is drawn then it does exactly as I expect.
Any clues? It seems like a fairly normal use of a NSTextStorageDelegate :)
I've tried calling -setNeedsDisplay on the text field to no avail.
Figured it out. Using NSTextStorage's -addAttribute:value:range works. I still don't fully understand why but at least I can get over it and move on.
-(void)textStorageDidProcessEditing:(NSNotification *)notification {
// ... SNIP ...
[textStorage addAttribute:NSForegroundColorAttributeName
value:[NSColor redColor]
range:NSMakeRange(1, 1)];
}
Makes the code a bit less cluttered too.
I'm not sure how relevant this is for you after so many years but I think the reason for it was that you were setting attributes with a dictionary which does not contain NSFontAttributeName, effectively removing it from the textview.
So I think this should work:
-(void)textStorageDidProcessEditing:(NSNotification *)notification {
NSTextStorage *textStorage = [textView textStorage];
if ([[textStorage string] length] > 1) {
NSColor *color = [NSColor redColor];
NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:color, NSForegroundColorAttributeName, [NSFont ...whatever...], NSFontAttributeName, nil];
[textStorage setAttributes:attributes range:NSMakeRange(1, 1)];
}
}
I have a situation where I need to use some strings temporarily but I've read so many conflicting things that I'm a bit confused as to what the best way to proceed is.
I need to assign some strings inside an if structure but use them outside the if structure so they need to be created outside the if, I was thinking something like:
NSString *arbString = [[NSString alloc] init];
if(whatever)
{
arbString = #"Whatever"
}
else
{
arbString = #"SomethingElse"
}
myLabel.text = arbString;
[arbString release];
I have seen examples where people just used:
NSString *arbString;
to create the string variable
Google's Objective C guide says it's preferred to autorelease at creation time:
"When creating new temporary objects, autorelease them on the same line as you create them rather than a separate release later in the same method":
// AVOID (unless you have a compelling performance reason)
MyController* controller = [[MyController alloc] init];
// ... code here that might return ...
[controller release];
// BETTER
MyController* controller = [[[MyController alloc] init] autorelease];
So I have no idea, which is the best practice?
In the example you posted, you actually lose the reference to the NSString you created when you assign it in arbString = #"Whatever". You then release the string constant (which is unreleasable, by the way).
So there's a memory leak, since you never release the NSString you created.
Remember that all these types are pointers, so = only reassigns them.
As for the question, in this example, you don't need the [[NSString alloc] init]. You don't need to copy the string into a local variable anyway, you can just set myLabel.text to the string constant #"Whatever".
(edit: that's not to say that you can't use your pointer arbString, arbString = #"Whatever"; myLabel.text = arbString is fine. But this is just pointer assignment, not copying)
If you needed to manipulate the string before you returned it, you would create an NSMutableString, and either release or auto-release it. Personally, create autoreleased objects using class methods, so in this example, I'd use [NSString string], or [NSString stringWithString:], which return autoreleased objects.
I have an method that reads an xml file and stores the xml nodes at a certain XPath-path in an NSArray called *nodes. What I want to do is take each one of the items in the array and add it to a core data entity called Category with the attribute of "name".
I have tried a number of different ways of creating the entity but I'm not sure about the correct way to do this effectively. This is the code used to create the NSArray, any ideas on how to implement this? (ignore the NSError, I will fix this in the final version)
- (IBAction)readCategories:(id)sender
{
NSString *xmlString = [resultView string];
NSData *xmlData = [xmlString dataUsingEncoding: NSASCIIStringEncoding];
NSXMLDocument *xmlDoc = [[NSXMLDocument alloc] initWithData:xmlData options:nil error:nil];
//XPath
NSError *err=nil;
NSArray *nodes = [xmlDoc nodesForXPath:#"//member[name='description']/value/string" error:&err];
}
EDIT - My loop code
NSArray *nodes = [xmlDoc nodesForXPath:#"//member[name='description']/value/string" error:&err];
int arrayCount = [nodes count];
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSXMLElement *categoryEl;
NSString *new = [catArrayController newObject];
int i;
for (i = 0; i < arrayCount; i++)
{
[categoryEl = [nodes objectAtIndex:i]];
[new setValue:[categoryEl stringValue] forKey:#"name"];
[catArrayController addObject:new];
}
[pool release];
Here's how I'd write it:
for (NSXMLElement *categoryElement in nodes) {
NSManagedObject *newObject = [catArrayController newObject];
[newObject setValue:[categoryElement stringValue] forKey:#"name"];
[catArrayController addObject:newObject];
[newObject release];
}
First, I'm using the Objective-C 2.0 for-each syntax. This is simpler than using index variables. I eliminated i and arrayCount.
Next, I took out your NSAutoreleasePool. None of the objects in the loop are autoreleased, so it had no effect. (The newObject method returns a retained object which is, by convention, what methods with the word new in their name do) This is also why I release newObject after adding it to the array controller. Since I'm not going to be using it any more in this method, I need to release it.
Also, you had defined new (which I renamed newObject) as an NSString. Core Data objects are always either an instance of NSManagedObject or a subclass of NSManagedObject.
Your line [categoryEl = [nodes objectAtIndex:i]] won't compile. That's because the bracket syntax is used to send a message to an object. This is an assignment statement, so the bracket syntax is not needed here. (This line is also not necessary any more because of I've changed the loop to use the for-each syntax) But, for future reference, categoryEl = [nodes objectAtIndex:i]; would have worked.
What part are you having trouble with? There shouldn't be much more to it than looping through the array, creating a new managed object for each entry, and setting the correct attributes. You can create the managed object with NSEntityDescription's -insertNewObjectForEntityForName:inManagedObjectContext: method.