Saving NSDictionary to plist: Serialization error

I have a dictionary with nested dictionaries (as per "flash cards") in my application. For some reason, the NSDictionary will not write to file. If I simply call writeToFile on my dictionary, it doesn't work, and NSPropertyListSerialization returns Property List invalid for Format. The code is as follows:

#import "flashCard.h"

#define kFront @"front"
#define kBack @"back"

@implementation flashCard

- (id) init
{
if (self = [super init])
{
    cards = [[NSDictionary alloc] initWithObjectsAndKeys:
             [[NSDictionary alloc] initWithObjectsAndKeys:
              @"aetas/aetatis", kFront,
              @"lifetime, age, generation", kBack,
              nil], [NSNumber numberWithInt: 1],
             [[NSDictionary alloc] initWithObjectsAndKeys:
              @"amicitia/amicitiae", kFront,
              @"alliance, friendship", kBack,
              nil], [NSNumber numberWithInt: 2],
             [[NSDictionary alloc] initWithObjectsAndKeys:
              @"amicus/amici", kFront,
              @"friend", kBack,
              nil], [NSNumber numberWithInt: 3],
             [[NSDictionary alloc] initWithObjectsAndKeys:
              @"animus/animi", kFront,
              @"mind, heart, spirit, courage", kBack,
              nil], [NSNumber numberWithInt: 4],
             nil];

    currentSide = [[NSString alloc] init];

    currentCard = 1;
    currentSide = kFront;
}

return self;
}

later, in the same implementation...

- (void) saveSet
{
NSLog(@"saveSet called");
NSSavePanel *cocaoSavePanel = [NSSavePanel savePanel];

int buttonPressed = [cocaoSavePanel runModal];
if (buttonPressed != NSOKButton)
{
    return;
}

NSLog(@"ok button, with url: %@", [cocaoSavePanel URL]);

NSError *error;
NSData *plistData = [NSPropertyListSerializati开发者_运维问答on dataWithPropertyList:cards
                     format:NSPropertyListXMLFormat_v1_0
                                                    options: 0
                     error: &error];

if (plistData)
{
    [plistData writeToURL:[cocaoSavePanel URL] atomically:YES];
    NSLog(@"File Saved Successfully");
}
else {
    NSLog(@"%@", error);
}
}

Any help would be appreciated.

EDIT: after revisions:

2011-08-12 13:00:47.937 flashcards[14452:a0f] saveSet called
2011-08-12 13:00:48.763 flashcards[14452:a0f] ok button, with url: file://localhost/Users/sam/Desktop/asdf
2011-08-12 13:00:48.764 flashcards[14452:a0f] {
    3 =     {
        back = friend;
        front = "amicus/amici";
    };
    2 =     {
        back = "alliance, friendship";
        front = "amicitia/amicitiae";
    };
    1 =     {
        back = "lifetime, age, generation";
        front = "aetas/aetatis";
    };
    4 =     {
        back = "mind, heart, spirit, courage";
        front = "animus/animi";
    };
}
2011-08-12 13:00:48.764 flashcards[14452:a0f] Property list invalid for format: 100
Program received signal:  “EXC_BAD_ACCESS”.
sharedlibrary apply-load-rules all

currentSide = [[NSString alloc] init];

currentCard = 1;
currentSide = kFront;

That leaks the empty NSString (or, would, but that [[NSString alloc] init] returns a singleton coincidentally). Also, you are leaking all of the dictionaries that you put into the outer cards dictionary.

Generally, when this kind of error pops up, it is because you have a non-plist-compatible object in your dictionaries/arrays; something that isn't an NSNumber, NSArray, NSDate, NSData, NSString, NSDictionary, etc....

NSLog(@"%@", cards); right before serialization and post that. Also what is the exact plist serialization format error?

I just copy/pasted your code and got:

asdfasdf[81731:707] Property list invalid for format (property list dictionaries may only have keys which are CFStrings, not 'CFNumber')

• you can't have keys that are numbers

• always read and post the entirety of the error messages spewed at runtime