writing NSDictionary to plist in my app bundle

I'm trying to write an NSDictionary to a plist but when I open the plist no data has been written to it. From the log my path looks correct and my code is pretty standard. Any ideas?

NSArray *keys = [NSArray arrayWithObjects:@"key1", @"key2", @"key3", nil];
NSArray *objects = [NSArray a开发者_运维问答rrayWithObjects:@"value1", @"value2", @"value3", nil];
NSDictionary *dictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];

for (id key in dictionary) {
    NSLog(@"key: %@, value: %@", key, [dictionary objectForKey:key]);
}

NSString *path = [[NSBundle mainBundle] pathForResource:@"FormData" ofType:@"plist"];
NSLog(@"path:%@", path);

[dictionary writeToFile:path atomically:YES];

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Johan is right -- you're not allowed to modify your app's bundle. You have two good options for where to save your dictionary: the documents directory, which is backed up by iTunes when a user syncs their device; or the caches directory, which is not backed up. If you don't need to have the data backed up, put it in caches so you don't slow down syncing. You can get the directory paths like so:

NSString *documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

NSString *cachesDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0];

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It doesn't get saved because you can't write into your app's bundle. Save your file elsewhere, in the documents folder for example.