Xcode 4.2 Example runs once then stuck

Question

I was having an issue, so I went back to a book example and found the same problem.  I am trying to create a very simple NSDictionary application under Cocoa.  At an early point I tried 'build and run' and it worked to bring up the screen I am constructing.  However, when I stop that run, and then repeat build and run, it never shows the screen.  It comes up with the following message and seems to be in a loop from there.  The number seems to be an almost random number.  I am sure it is a novice error, but it is stopping all progress!  Any help would be appreciated.
tty /dev/ttys000
[Switching to process 4792 thread 0x0]

Answer 1

Thanks.  The code is pretty short, so I am including it all.  It really is beginner level.  I am sure I just need an experienced eye to point out some mis-direction on my part.  Thanks for any coaching I can get.  I only wrote the first method and added a line to the init method.  It has occurred to me that perhaps this has something to do with the upgrade from Xcode 3.x to Xcode 4.2.  The book example I am following was written to Xcode 3.  The book examples had similar errors with NSDictionary and NSArray examples.
Document.h
#import <Cocoa/Cocoa.h>
@interface Document : NSDocument
    NSMutableDictionary *mainDictionary;
    IBOutlet NSTextField *kRefInField;
    IBOutlet NSTextField *dataInField;
- (IBAction)storeRefAndData: (id)sender;
@end
Document.m
#import "Document.h"
@implementation Document
- (IBAction)storeRefAndData: (id)sender
    NSString *kRefToStore = [kRefInField stringValue];
    NSString *dataToStore = [dataInField stringValue];
    [mainDictionary setValue:dataToStore forKey:kRefToStore];
- (id)init
    self = [super init];
    if (self) {
        // Add your subclass-specific initialization here.
        // If an error occurs here, return nil.
        mainDictionary = [[NSMutableDictionary alloc] init];
    return self;
- (NSString *)windowNibName
    // Override returning the nib file name of the document
    // If you need to use a subclass of NSWindowController or if your document supports multiple NSWindowControllers, you should remove this method and override -makeWindowControllers instead.
    return @"Document";
- (void)windowControllerDidLoadNib:(NSWindowController *)aController
    [super windowControllerDidLoadNib:aController];
    // Add any code here that needs to be executed once the windowController has loaded the document's window.
- (NSData *)dataOfType:(NSString *)typeName error:(NSError **)outError
     Insert code here to write your document to data of the specified type. If outError != NULL, ensure that you create and set an appropriate error when returning nil.
    You can also choose to override -fileWrapperOfType:error:, -writeToURL:ofType:error:, or -writeToURL:ofType:forSaveOperation:originalContentsURL:error: instead.
    NSException *exception = [NSException exceptionWithName:@"UnimplementedMethod" reason:[NSString stringWithFormat:@"%@ is unimplemented", NSStringFromSelector(_cmd)]userInfo:nil];
    @throw exception;
    return nil;
- (BOOL)readFromData:(NSData *)data ofType:(NSString *)typeName error:(NSError **)outError
    Insert code here to read your document from the given data of the specified type. If outError != NULL, ensure that you create and set an appropriate error when returning NO.
    You can also choose to override -readFromFileWrapper:ofType:error: or -readFromURL:ofType:error: instead.
    If you override either of these, you should also override -isEntireFileLoaded to return NO if the contents are lazily loaded.
    NSException *exception = [NSException exceptionWithName:@"UnimplementedMethod" reason:[NSString stringWithFormat:@"%@ is unimplemented", NSStringFromSelector(_cmd)]userInfo:nil];
    @throw exception;
    return YES;
+ (BOOL)autosavesInPlace
    return YES;
@end
Re: [Switching to process 2576 thread 0x0]