In my app I have a table view where the user presses an "add" button in the nav bar and a new cell is added to the table view. The data from the table is loaded from an NSArray and each index in the array is storing an NSMutableDictionary with 4 Key-Value pairs. This array is saved to a .plist every time a cell is added. Now when the user selects a row in the table a detail view gets loaded. This detail view simply loads the data from the saved .plist depending on what row was selected.
In this detail view I want to allow the user to edit the data in the dictionary for that specific row. I've been trying different things and I can read the data from the dictionary and load it into the view but when I try and save the data back to the dictionary my app keeps terminating.
Can someone explain to me the proper way to reading and writing data to a an NSMutableDictionary?
This is how i'm writing the data back to the .plist:
NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:filePath];
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
dict = [array objectAtIndex:selectedRow];
NSString *tempA = [[NSString alloc] initWithFormat:#"%d pts", ivar_A];
NSString *tempB = [[NSString alloc] initWithFormat:#"%d pts", ivar_B];
NSString *tempC = [[NSString alloc] initWithFormat:#"%d pts", ivar_C];
[dict setValue:tempA forKey:#"keyA"];
[dict setValue:tempB forKey:#"keyB"];
[dict setValue:tempC forKey:#"keyC"];
[tempA release];
[tempB release];
[tempC release];
[array insertObject:dict atIndex:selectedRow];
//Save the modified array back to the plist
[array writeToFile:[self dataFilePath] atomically:YES];
[dict release];
[array release];
if you use [[NSMutableDictionary alloc] dictionaryFromContentsOfFile:#"pathtofile.plist], the contents of the dictionary will still be immutable, even if the top level container is mutable. It is specifically stated in Apple's reference.
NSDictionary Reference
The dictionary representation in the
file identified by path must contain
only property list objects (NSString,
NSData, NSDate, NSNumber, NSArray, or
NSDictionary objects). For more
details, see Property List Programming
Guide. The objects contained by this
dictionary are immutable, even if the
dictionary is mutable.
If you need to make the data structure writable again, you will need to make a copy of the loaded data structure using mutable types, like
[NSMutableDictionary dictionaryWithDictionary:oOrig]
etc.
Related
In this code from an array i am selecting a dictionary,modifying it and saving back in another array .but i dont know why at the second last line of this code ie where i am inserting the dict it is crashing (message sent to deallocated instance).how can i fix this
NSArray *array=[NSArray arrayWithContentsOfFile:plistPath];
NSLog(#"array before %#",array);
NSMutableArray *tempArray=[[NSMutableArray alloc]init];
tempArray=(NSMutableArray*)array;
NSMutableDictionary *dictToBeChanged=[[NSMutableDictionary alloc]init];
dictToBeChanged=[tempArray objectAtIndex:indexPath.row];
[dictToBeChanged setObject:[NSNumber numberWithBool:YES] forKey:#"isPaid"];
[tempArray removeObjectAtIndex:indexPath.row];
[tempArray insertObject:dictToBeChanged atIndex:indexPath.row];
NSLog(#"array after %#",tempArray);
When you assign array to tempArray you don't make it mutable just because you cast it.
It's an NSArray, so you can't add/remove its objects.
Also, there are a few unneeded initializations (of tempArray and dictToBeChanged) since you're overwriting those variables with something else right after initializing (thus creating leaks).
What you need is probably something like this:
NSMutableArray *array = [NSMutableArray arrayWithContentsOfFile:plistPath];
NSMutableDictionary *dictToBeChanged = [[[array objectAtIndex:indexPath.row] mutableCopy] autorelease];
[dictToBeChanged setObject:[NSNumber numberWithBool:YES] forKey:#"isPaid"];
[array replaceObjectAtIndex:indexPath.row withObject:dictToBeChanged];
Note that this code doesn't do any validations on the contents of your plist.
You may want to add the objects to tempArray as the temparray as follows:
[tempArray addObjectsFromArray:array];
try this
NSMutableArray *temp;
temp=[temp arrayByAddingObjectsFromArray:(NSArray *)otherArray];
You are looking at a memory management issue. Try this:
NSMutableArray *array = [NSMutableArray arrayWithContentsOfFile:plistPath];//Temp array is unecessary
NSMutableDictionary *dictToBeChanged; //No need to allocate a new instance
Not directly related but:
Both of your alloc [init] calls are unnecessary and causing leaks. Basically what you are doing is creating a new blank array with the allocation and and assigning it to a variable. Then you immediately assign your variable to another array, losing the reference to the blank array/dictionary you just created, which means it can't get released. If you are calling release later in your code it will cause trouble.
I have a simple code:
NSMutableArray *arrayCheckList = [[NSMutableArray alloc] init];
[arrayCheckList addObject:[NSMutableDictionary dictionaryWithObjects:[NSArray arrayWithObjects:#"2011-03-14 10:25:59 +0000",#"Exercise at least 30mins/day",#"1",nil] forKeys:[NSArray arrayWithObjects:#"date",#"checkListData",#"status",nil]] ];
[arrayCheckList addObject:[NSMutableDictionary dictionaryWithObjects:[NSArray arrayWithObjects:#"2011-03-14 10:25:59 +0000",#"Take regular insulin shots",#"1",nil] forKeys:[NSArray arrayWithObjects:#"date",#"checkListData",#"status",nil]]];
Now I want to add a specific index of above array to a dictionary. Below are two way, which one is better and why? What are the specific drawbacks of the latter?
NSDictionary *tempDict = [[NSDictionary alloc] initWithDictionary:[arrayCheckList objectAtIndex:1]];
OR
NSDictionary *tempDict = [arrayCheckList objectAtIndex:1];
What would the impact on the latter since I am not doing any alloc/init in it?
1:
NSDictionary *tempDict = [[NSDictionary alloc] initWithDictionary:[arrayCheckList objectAtIndex:1]];
Creates a new immutable dictionary object as a copy of the original one. If you add objects to the mutable dictionary in your arrayCheckList they will not be added to your copied reference.
2:
NSDictionary *tempDict = [arrayCheckList objectAtIndex:1];
This directly pulls the mutable dictionary from your array and not a copy. The following two lines will be equivalent:
[[arrayCheckList objectAtIndex:1] addObject:something];
[tempDict addObject:something];
The first one potentially copies the dictionary a index 1 of the array. (It should, since you're creating an immutable dictionary but the one in the array is mutable.) The second only gets a reference to the dictionary in the array -- there's no chance of creating a new object.
Suppose I am holding data in an array like this
wordList = [[NSMutableArray alloc] init];
while ([rs next]) //Some database return loop
{
wordDict = [[NSMutableDictionary alloc] init];
[wordDict setObject:[NSNumber numberWithInt:[rs intForColumn:#"id"]] forKey:#"id"];
[wordDict setObject:[rs stringForColumn:#"word"] forKey:#"word"];
[wordList addObject: wordDict];
[wordDict release];
wordDict = nil;
}
But I want to store this result (i.e. wordList) in SQLite for later use - I guess using NSCoding. How would I do that?
(Feel free to point out any errors in how stuff is being alloc'ed if there are problems there).
If you don’t insist on serialization using NSCoding, there’s a writeToFile:atomically: method both on NSArray and NSDictionary. This will serialize your object into a property list (*.plist). The only catch is that all the objects in the “tree” to be serialized must be NSString, NSData, NSArray, or NSDictionary (see the documentation). I’m not sure how NSNumber fits in, but with a bit of luck it will be serialized and deserialized too. The inverse method that will turn the file back into a dictionary or an array is called initWithContentsOfFile:.
As for your code, I would just use the [NSMutableDictionary dictionary] convenience method that gets you an autoreleased dictionary. It’s shorter than the usual alloc & init and you save one line for the explicit release.
I have run into this issue and have put some major time into finding the answer. I am somewhat new to objective c but not to programming.
Here is my question.
I have a plist file with this structure
root {
A (
{songTitle : contents of song},
{songTitle : contents of song}
),
B (
{songTitle : contents of song}
),
C (
{songTitle : contents of song}
),
... kepps going
}
Sorry if the the plist structure is not correct.
Pretty much I have a root dictionary (that is what it comes with) that contains an array of A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,...Z (alphabet)
Each letter of the alphabet array contains 1 or more dictionaries that have a key, value pair of songTitle (this could be any string) as the key and the song lyrics for the value.
My issue here is I need to create an array of all song titles and have been having a rough time trying to find out how to do this. I own 4 books on object c and none of them go into detail about multidimensional arrays and how to access pieces inside them.
I have created an array with all the letters and have created an array that contains the objects from each letter.
Like I stated before I need to find out how to make an array that contains each song title.
If you can help me that would save me a lot of time.
Thanks,
Wes
I am guessing you are suggesting I change my root from a dictionary to an array?
Maybe it might be better to show my code here.
Also I have attached an updated version of my plist file
Sorry seems I cannot add the image here but you can view it
http://www.wesduff.com/images/forum_images/plist_examp.png
So as you can see I have updated the plist file to show the array of letters that each contain multiple dictionaries. Each dictionary has a songTitle and a songLyrics.
How can I write code to get an array of songTitles.
Here is what I have come up with so far
NSString *path = [[NSBundle mainBundle] pathForResource:#"songs" ofType:#"plist"];
NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:path];
//This gives me an array of all the letters in alphabetical order
NSArray *array = [[dict allKeys] sortedArrayUsingSelector:#selector(compare:)];
/**
Now I need to find out how to get an array of all songTitles
**/
I am still working on this and looking through what others have written but have not found anything yet.
As the first answer has suggested, should I change the root to an array or keep it as I have it in this plist image I have attached.
Thanks again,
Wes
Ok so I did some more digging and came up with this from the plist file that was included in this picture
http://www.wesduff.com/images/forum_images/plist_examp.png
- (void)viewDidLoad {
//path for plist file
NSString *path = [[NSBundle mainBundle] pathForResource:#"songList" ofType:#"plist"];
//dictionary created from plist file
NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:path];
//release the path because it is no longer needed
[path release];
//temp array to hold an array of all alphabetical letters
NSArray *array = [[dict allKeys] sortedArrayUsingSelector:#selector(compare:)];
//assign array to allLetters array
self.allLetters = array;
//Create two mutable arrays for the songArray (could do a little cleaner job of this here)
NSMutableArray *songArray = [[NSMutableArray alloc] init];
NSMutableArray *songTitles = [[NSMutableArray alloc] init];
//Add messy array to songArray then we can work with the songArray (maybe something better to do here)
for(id key in dict)
{
[songArray addObject:[dict objectForKey:key]];
}
//temp array to hold a messy array for all of the songTitles
NSArray *tempArray = [songArray valueForKey:#"songTitle"];
//go through the temparray and clean it up to make one array of all song titles and sort them
for (NSUInteger i = 0; i < [tempArray count]; i++) {
[songTitles addObjectsFromArray:[[tempArray objectAtIndex:i] sortedArrayUsingSelector:#selector(compare:)]];
}
//assign all song titles to our array of songTitles
self.allSongTitles = songTitles;
[dict release];
[allSongTitles release];
[songArray release];
[tempArray release];
[array release];
[super viewDidLoad];
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem;
}
I am sure there is probably a better way to do this but this is what I have come up with on my own. Thanks
If you have single array with the contents of all the letters, the rest is fairly simple. Iterate through the objects and call the dictionary method allKeys on each one. Each call to allKeys will return an NSArray containing the keys of that specific dictionary, which you can then place into another array.
EDIT
I made a mistake, didn't go deep enough. This is what I would do:
NSString *path = [[NSBundle mainBundle] pathForResource:#"songs" ofType:#"plist"];
NSDictionary plistDict = [NSDictionary dictionaryWithContentsOfFile:path]; //not using alloc and init means this isn't retained, so it will be autoreleased at the end of the method
NSArray *allLetterContents = [plistDict allValues]; // array of arrays, where each element is the content of a 'letter' in your plist (i.e. each element is an array of dictionaries)
NSMutableArray *allSongTitles = [[[NSMutableArray alloc] init] autorelease];
for(NSArray *oneLetterContents in allLetterContents)
{
for(NSDictionary *song in oneLetterContents)
{
[allSongTitles addObject:[song objectForKey:#"songTitle"]]
}
}
return allSongTitles;
This array isn't guaranteed to be sorted alphabetically, so you'll have to call [sortedArrayUsingSelector:] on it.
Reference:
NSMutableArray Class Reference
NSDictionary Class Reference
I have been trying to get this to work for about three solid days and get my mind around it. Can someone advise.
I have built the basics and they all work great but when I try to do that extra bit I cannot get my head around it.
I am trying to build a table of technical terms, from a plist. This is an indexed and sections table by the alphabet.
This works fine but when I then try to add the next level for each term's definition in a new viewcontroller I can't seem to get the code or the plist structure right.
At the moment I have created two plists. One with a dictionary of the alphabet in 26 arrays, within each array is a series of technical terms. All this works great.
Then I've created another plist of definitions as an array of dictionaries, one for each word/definition pair. I'm expecting to be passing the #"word" key from the view controller to the detailviewcontroller then picking up the #"definition". I don't know whether this is right or wrong(?)
My code shows the technical term table great but when a row is selected it crashes. I know it's to do with the code for passing the detailviewcontroller's reference so the detailview can pick up the definition - but I've no idea how to solve it. I've posted parts of my code here for someone to look at help. Any ideas?
NSString *wordPath = [[NSBundle mainBundle] pathForResource:#"newsortedglossary" ofType:#"plist"];
NSDictionary *wordDict = [[NSDictionary alloc] initWithContentsOfFile:wordPath];
self.words = wordDict;
[words release];
NSArray *wordArray = [[words allKeys] sortedArrayUsingSelector:#selector(compare:)];
self.wordKeys = wordArray;
NSString *definitionPath = [[NSBundle mainBundle] pathForResource:#"newnewdefinitionglossary" ofType:#"plist"];
NSDictionary *definitionDict = [[NSDictionary alloc] initWithContentsOfFile:definitionPath];
self.definitions = definitionDict;
[definitions release];
didSelectRow here.........
GlossaryDetailViewController *glossaryDetailViewController = [[GlossaryDetailViewController alloc]
initWithNibName:#"GlossaryDetailView" bundle:nil];
NSLog(#"did select-2"); // CRASHES HERE with NSDictionary may not respond to objectAtIndex
glossaryDetailViewController.definition = [self.words objectAtIndex:indexPath.row];
NSLog(#"did select-3");
[self.navigationController pushViewController:glossaryDetailViewController animated:YES];
NSLog(#"did select-4");
[glossaryDetailViewController release];
detailViewController here.......
- (void)viewDidAppear:(BOOL)animated {
NSLog(#"didappear");
self.glossaryWordDefinition.text = [definition objectForKey:#"definition"];
It seems that you are trying to access the members of dictionary by using an index, instead of using a key to lookup the associated value.
In your didSelectRow you probably want this:
glossaryDetailViewController.definition = [self.wordKeys objectAtIndex:indexPath.row];
The difference is that now you are trying access the members of an array with the index.