CoreData, transient attribute and EXC_BAD_ACCESS. - objective-c

Question

I'm trying to build simple file browser and i'm stuck.
I defined classes, build window, add controllers, views.. Everything works but only ONE time.
Selecting again Folder in NSTableView or trying to get data from Folder.files causing silent EXC_BAD_ACCESS (code=13, address0x0) from main.
Info about files i keep outside of CoreData, in simple class, I don't want to save them:
#import <Foundation/Foundation.h>
#interface TPDrawersFileInfo : NSObject
#property (nonatomic, retain) NSString * filename;
#property (nonatomic, retain) NSString * extension;
#property (nonatomic, retain) NSDate * creation;
#property (nonatomic, retain) NSDate * modified;
#property (nonatomic, retain) NSNumber * isFile;
#property (nonatomic, retain) NSNumber * size;
#property (nonatomic, retain) NSNumber * label;
+(TPDrawersFileInfo *) initWithURL: (NSURL *) url;
#end
#implementation TPDrawersFileInfo
+(TPDrawersFileInfo *) initWithURL: (NSURL *) url {
TPDrawersFileInfo * new = [[TPDrawersFileInfo alloc] init];
if (new!=nil) {
NSFileManager * fileManager = [NSFileManager defaultManager];
NSError * error;
NSDictionary * infoDict = [fileManager attributesOfItemAtPath: [url path] error:&error];
id labelValue = nil;
[url getResourceValue:&labelValue forKey:NSURLLabelNumberKey error:&error];
new.label = labelValue;
new.size = [infoDict objectForKey: #"NSFileSize"];
new.modified = [infoDict objectForKey: #"NSFileModificationDate"];
new.creation = [infoDict objectForKey: #"NSFileCreationDate"];
new.isFile = [NSNumber numberWithBool:[[infoDict objectForKey:#"NSFileType"] isEqualToString:#"NSFileTypeRegular"]];
new.extension = [url pathExtension];
new.filename = [[url lastPathComponent] stringByDeletingPathExtension];
}
return new;
}
Next I have class Folder, which is NSManagesObject subclass
// Managed Object class to keep info about folder content
#interface Folder : NSManagedObject {
NSArray * _files;
}
#property (nonatomic, retain) NSArray * files; // Array with TPDrawersFileInfo objects
#property (nonatomic, retain) NSString * url; // url of folder
-(void) reload; //if url changed, load file info again.
#end
#implementation Folder
#synthesize files = _files;
#dynamic url;
-(void)awakeFromInsert {
[self addObserver:self forKeyPath:#"url" options:NSKeyValueObservingOptionNew context:#"url"];
}
-(void)awakeFromFetch {
[self addObserver:self forKeyPath:#"url" options:NSKeyValueObservingOptionNew context:#"url"];
}
-(void)prepareForDeletion {
[self removeObserver:self forKeyPath:#"url"];
}
-(void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if (context == #"url") {
[self reload];
}
}
-(void) reload {
NSMutableArray * result = [NSMutableArray array];
NSError * error = nil;
NSFileManager * fileManager = [NSFileManager defaultManager];
NSString * percented = [self.url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSArray * listDir = [fileManager contentsOfDirectoryAtURL: [NSURL URLWithString: percented]
includingPropertiesForKeys: [NSArray arrayWithObject: NSURLCreationDateKey ]
options:NSDirectoryEnumerationSkipsHiddenFiles
error:&error];
if (error!=nil) {NSLog(#"Error <%#> reading <%#> content", error, self.url);}
for (id fileURL in listDir) {
TPDrawersFileInfo * fi = [TPDrawersFileInfo initWithURL:fileURL];
[result addObject: fi];
}
_files = [NSArray arrayWithArray:result];
}
#end
In app delegate i defined
#interface TPAppDelegate : NSObject <NSApplicationDelegate> {
IBOutlet NSArrayController * foldersController;
Folder * currentFolder;
}
- (IBAction)chooseDirectory:(id)sender; // choose folder
and
- (Folder * ) getFolderObjectForPath: path {
//gives Folder object if already exist or nil if not
.....
}
- (IBAction)chooseDirectory:(id)sender {
//Opens panel, asking for url
NSOpenPanel * panel = [NSOpenPanel openPanel];
[panel setCanChooseDirectories:YES];
[panel setCanChooseFiles:NO];
[panel setMessage:#"Choose folder to show:"];
NSURL * currentDirectory;
if ([panel runModal] == NSOKButton)
{
currentDirectory = [[panel URLs] objectAtIndex:0];
}
Folder * folderObject = [self getFolderObjectForPath:[currentDirectory path]];
if (folderObject) {
//if exist:
currentFolder = folderObject;
} else {
// create new one
Folder * newFolder = [NSEntityDescription
insertNewObjectForEntityForName:#"Folder"
inManagedObjectContext:self.managedObjectContext];
[newFolder setValue:[currentDirectory path] forKey:#"url"];
[foldersController addObject:newFolder];
currentFolder = newFolder;
}
[foldersController setSelectedObjects:[NSArray arrayWithObject:currentFolder]];
}
Please help ;)

Answer 1

Ha!
_files = [NSArray arrayWithArray:result];
Should be:
_files = [[NSArray arrayWithArray:result] retain];