I have a array (dataArray) of NSDictionary "item". It has datas like "david" for key "name" and "85" for key "marks" etc for 5 students. I want to replace the mark of david to 90 with respect to the array index value (ie 0 for dictionary containing david and 85). How can I do it?
The code for content in array is
[item setobject:name forkey:#"Name"];
[item setobject:mark forkey:#"Marks"];
[dataArray addOject:item]
The above code goes inside parsing, so i have array with 5 objects (students), their name and marks, now I want to replace the mark of the first object in the dataArray.
Here's what you can do:
NSMutableDictionary *newDict = [[NSMutableDictionary alloc] init];
NSDictionary *oldDict = (NSDictionary *)[dataArray objectAtIndex:0];
[newDict addEntriesFromDictionary:oldDict];
[newDict setObject:#"Don" forKey:#"Name"];
[dataArray replaceObjectAtIndex:0 withObject:newDict];
[newDict release];
Hope this helps!
You first need an NSMutableDictionary with it you can change the key and value.
It would be like this:
NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithObjectsAndKeys:#"david", #"name", "85", #"marks", nil];
[dict setObject:#"90" forKey:#"david"];
// NSDictionary *dict = ...
NSMutableDictionary *mutableDict = [dict mutableCopy];
[mutableDict setObject:#"myObject" forKey:#"myKey"];
dict = [mutableDict mutableCopy];
I hope it helps
If you want to update an object in a NSDictionary you should use NSMutableDictionary instead.
NSMutableDictionary has the following EXTRA methods
Adding Entries
setObject:forKey:
setValue:forKey:
addEntriesFromDictionary:
setDictionary:
Removing Entries
removeObjectForKey:
removeAllObjects
removeObjectsForKeys:
[davidsRecord setObject:#"100" forkey:#"mark"];
Related
Here i am using NSMutableArray to store date, then i tried to set key and assign ArrayValue in dictionary but the app crashed, please help me
Thanks in ADvance
Here i tried the code for your reference:
[DateArray addObject:dateString]; //NSMutablArray
NSMutableDictionary *myDictionary =[[NSMutableDictionary alloc]init];
[myDictionary setObject:DateArray forKey:#"Date"]; //put array value and set key in NSDictionary.
NSDictionary Class is immutable. You must convert to NSMutableDictionary.
If you are using XCode version 4.4 or later you can jus do this:
[dateArray addObject:dateString]; //NSMutablArray
NSDictionary *myDictionary = #{ #"Date", dateArray };
You are using NSDictionary. You should use NSMutableDictionary.
NSDictionary is immutable. If you want to use NSDictionary then use below method:
- (id)initWithObjects:(NSArray *)objects forKeys:(NSArray *)keys;
You're using an NSDictionary when you should be using NSMutableDictionary
Try this line :
NSMutableDictionary *myDictionary = [[NSMutableDictionary alloc] init];
Most of the collection classes in iOS have a mutable and nonmutable version (i.e.
NSArray -> NSMutableArray
NSSet -> NSMutableSet
NSDictionary -> NSMutableDictionary
(and others)
A mutable version will let you modify the contents. However, if you know you're not going to change it then a non mutable version will be slightly faster to use.
You can (usually) get a mutable class from a nonmutable one by using the mutableCopy method i.e.
// This array can't be changed
NSArray *myArray = #[ #"A", #"B", #"C" ];
// This array contains everything from the previous array but can now be modified
MSMutableArray myArray2 = [myArray mutableCopy];
NB : There are also other classes that have mutable subclasses i.e. NSURL -> NSMutableURL
Do it like this:
for(int i=0;i<[DateArray count]; i++)
{
[myDictionary addObject:[DateArray objectAtIndex:i] forKey:#"Date"];
}
I am trying to retrieve the values from my NSDictionary however I am running into errors, I was wondering if someone might be able to help me with my solution.
I have 18 values, not all are shown here that I am checking, when the correct key is reached I would like to take the value in the NSDictionary and pass it into one of my NSString variables.
Below is an example of what I am trying to do however like I say I am having several issues
for (id key in searchData) {
if ([[searchData objectForKey:key] isEqualToString:#"Code"]) {
codeSeries = [searchData objectForKey:key];
}
else if ([[searchData objectForKey:key] isEqualToString:#"ID"]) {
IDSeries = [searchData objectForKey:key];
}
// ...
However, when I try to log out any of the values, they all return Null. I have checked the dictionary before hand and the values are all most definitely in there, so I am thinking there is something wrong with my code above.
Any help would be greatly appreciated.
Update
This is how I create the NSDictionary
//start of mymethod...
NSDictionary *sendSeriesDictionary = [[NSDictionary alloc] init];
// Keys for sendSeriesDictionary
NSArray *keys = [NSArray arrayWithObjects:#"Code", #"ID", nil];
// Objects for keys that are for sendSeriesDictionary
NSArray *objects = [NSArray arrayWithObjects: [NSNull null], IdString, nil];
// Add keys and objects to NSDictionary
sendSeriesDictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
[engineRequests SeriesSearch:sendSeriesDictionary]; // this is where I send the NSDictionary over to where I want to read it.
//end of mymethod
You've got several problems. First, you mix up keys and values (like Tom said). Second, you have a possible memory leak where you create the dictionary, or at least a unnecessary instantiation.
Try this for creating the dictionary:
// Keys for sendSeriesDictionary
NSArray *keys = [NSArray arrayWithObjects:#"Code", #"ID", nil];
// Objects for keys that are for sendSeriesDictionary
NSArray *objects = [NSArray arrayWithObjects: [NSNull null], IdString, nil];
// Add keys and objects to NSDictionary
NSDictionary *sendSeriesDictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
Retrieving the values can be done like this:
codeSeries = [searchData objectForKey:#"Code"];
IDSeries = [searchData objectForKey:#"ID"];
In your first loop you looped through all the keys, got their values and then compared those to the key again. Which makes no sense.
Are you mixing keys and values ?
Maybe you just want codeSeries = [searchData objectForKey:#"Code"]; ?
So I have an array of NSDictionaries, each NSDictionary has a bunch of key/value pairs pertaining to aspects of a photo (from Flickr).
I'm making an app that has a UITableViewController whose cells should be each of the different categories of the photos. So in pseudocode, I'm trying to construct a new NSDictionary (with keys being categories of photos, values being the NSDictionaries of the photos that contains that key). I'm iterating through each NSDictionary in the initial array, getting the category tags, and saying, if my new NSDict doesn't contain this key, make a new key to an empty array. Then add the current NSDict to that array. I'm getting consistent errors, not sure why.
Here's the diluted code.
photoList = [FlickrFetcher photosWithTags:[NSArray arrayWithObjects: #"CS193p_SPoT", nil]];
NSLog(#"%#", photoList);
categories = [[NSDictionary alloc] init];
NSArray *temp = [[NSArray alloc] init];
for (id obj in photoList) {
temp = [[obj objectForKey:#"tags"] componentsSeparatedByString:#" "];
for (id string in temp) {
if (![categories objectForKey:string]) {
NSMutableArray *arr = [[NSMutableArray alloc] init];
[categories setObject:arr forKey:string];
//[arr release];
}
NSMutableArray *photos = [categories objectForKey:string];
[photos addObject:obj];
[categories setObject:photos forKey:string];
}
}
Thanks!
NSDictionary doesn't have a method setObject:forKey:. You need an NSMutableDictionary.
self.categories = [NSMutableDictionary dictionary];
Other than that, please do use Joost's excellent rewrite of your code.
SIGABRT, just so you know, most likely means that an assertion somewhere failed. In this case, it may be an assertion all the way down in CoreFoundation*; CF checks for mutability when you try to access a dictionary like that and causes an interrupt if the object isn't mutable.
*I have just learned about the CF source's availability recently and have been looking through it, so this may be just "new thing" bias and incorrect.
I don't notice any errors (syntax-errors, that is) in your code, however here is an updated piece of code which has been implemented a bit cleaner (and without memory leaks)
self.photoList = [FlickrFetcher photosWithTags:[NSArray arrayWithObjects: #"CS193p_SPoT", nil]];
NSLog(#"%#", photoList);
self.categories = [NSDictionary dictionary];
for (NSDictionary *obj in photoList) {
NSArray *temp = [[obj objectForKey:#"tags"] componentsSeparatedByString:#" "];
for (NSString *string in temp) {
NSMutableArray *photos = [categories objectForKey:string];
if (!photos) {
photos = [NSMutableArray array];
[categories setObject:photos forKey:string];
}
[photos addObject:obj];
}
}
If it's not working please tell us the exact warning, and were it is caused.
I have a NSMutableArray (i.e. "stories") of dictionary items.
I can read the dictionary items in the array just fine, e.g.
[[[stories objectAtIndex: b] objectForKey: #"title"]
But, now I am trying to update (i.e. replace) a couple of objects e.g. "title" & "matchingword", but I cannot find the right code. Any suggestions are much appreciated.
I tried this, but it seems to be adding entirely new objects to the array
NSMutableDictionary *itemAtIndex = [[NSMutableDictionary alloc]init];
[itemAtIndex setObject:[[placesArray objectAtIndex:a]objectAtIndex:0] forKey:#"reference"];
[stories replaceObjectAtIndex:x withObject:itemAtIndex]; // replace "reference" with user's unique key
[itemAtIndex release];
I also tried this (but didn't work either):
//NSMutableDictionary *itemAtIndex2 = [[NSMutableDictionary alloc]init];
//[itemAtIndex2 setObject:[separatePlaces objectAtIndex:x] forKey:#"matchingword"];
//[stories insertObject:itemAtIndex2 atIndex:x]; // add the unique matching word to story
//[itemAtIndex2 release];
Help appreciated. Thanks.
You need to grab the dictionary you want to mod.
NSMutableDictionary *temp = [stories objectAtIndex: b];
The change the value:
[temp setObject:#"new Info" forKey:#"title"];
I want to programatically create a dictionary which feeds data to my UITableView but I'm having a hard time with it. I want to create a dictionary that resembles this property list (image) give or take a couple of items.
I've looked at "Property List Programming Guide: Creating Property Lists Programmatically" and I came up with a small sample of my own:
//keys
NSArray *Childs = [NSArray arrayWithObjects:#"testerbet", nil];
NSArray *Children = [NSArray arrayWithObjects:#"Children", nil];
NSArray *Keys = [NSArray arrayWithObjects:#"Rows", nil];
NSArray *Title = [NSArray arrayWithObjects:#"Title", nil];
//strings
NSString *Titles = #"mmm training";
//dictionary
NSDictionary *item1 = [NSDictionary dictionaryWithObject:Childs, Titles forKey:Children , Title];
NSDictionary *item2 = [NSDictionary dictionaryWithObject:Childs, Titles forKey:Children , Title];
NSDictionary *item3 = [NSDictionary dictionaryWithObject:Childs, Titles forKey:Children , Title];
NSArray *Rows = [NSArray arrayWithObjects: item1, item2, item3, nil];
NSDictionary *Root = [NSDictionary dictionaryWithObject:Rows forKey:Keys];
// NSDictionary *tempDict = [[NSDictionary alloc] //initWithContentsOfFile:DataPath];
NSDictionary *tempDict = [[NSDictionary alloc] initWithDictionary: Root];
I'm trying to use this data of hierachy for my table views.
So I was wondering how can I can create my property list (dictionary) programmatically so that I can fill it with my own arrays.
I'm still new with iPhone development so bear with me. ;)
This is a situation where "teach a man to fish" is a vastly more helpful approach than "give a man a fish". Once you understand the basic principles and the NSDictionary API, it becomes much easier to craft your own custom solution. Here are a few observations and learning points:
The method +dictionaryWithObject:forKey: is used to create an NSDictionary with a single key-value pair. It will not accept comma-separated arguments after each colon (:) in the method call, just one. To create a dictionary with multiple key-value pairs, use one of 2 related methods: +dictionaryWithObjects:forKeys: which accepts two NSArray objects containing values and keys, or +dictionaryWithObjectsAndKeys: which alternates (object, key, object, key) with a terminating nil argument.
Simplify the creation code. You don't need a million local variables just to create the thing. Use inline arguments where it makes sense. One way to do this it to build up your dictionary in code as an NSMutableDictionary, then (if necessary) make an immutable copy of it by calling -copy on it. (Remember that a copy method returns a new object that you must release to avoid memory leaks.) That way you don't have to have a variable for every single value so you can do a "one shot" creation of the structure(s) at each level.
Use +arrayWithObject: for creating an NSArray with a single object.
(Style suggestions) Never use an uppercase letter to begin the name of a variable, method, or function. (Notice that SO highlights leading-caps variables like class names.) It will certainly help others who read your code from being confused about your intent by your naming scheme.
Just to give you a flavor of what creating the dictionary in the linked image might look like in code... (I'm ignoring your chosen variable names and using both different approaches for completeness.)
NSDictionary *item1 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:#"Screen J",[NSNumber numberWithInt:3],nil]
forKeys:[NSArray arrayWithObjects:#"Title",#"View",nil]];
NSDictionary *item2 = [NSDictionary dictionaryWithObjectsAndKeys:
#"Screen I", #"Title",
[NSArray arrayWithObject:item1], #"Children",
nil];
...
I am not sure I understand the basic objective here.
It seems like at runtime, you are constructing a deep dictionary with many child nodes. But you are constructing this all with static code... why can you not simply make a plist (like the one you had an image of) and read that into an NSDictionary? Both NSDictionary and NSArray have methods that let you simply read in a file and get a whole filled out object. Then it is WAY easier to edit and to understand. That method is dictionaryWithContentsOfFile.
If all of the data is truly created at runtime before it is put into the dictionary, then it seems like you would want a very different, recursive, style of code rather than the flat examples given.
Lastly, I personally dislike the dictionaryWithObjects:forKeys: method in NSDictionary for building a dictionary. If you have to do things that way I greatly prefer the alternate method dictionaryWithObjectsAndKeys: which does the same thing but keeps the keys with the objects:
NSDictionary *item1 = [NSDictionary dictionaryWithObjectsAndKeys:
#"Screen J",
#"Title",
[NSNumber numberWithInt:3],
#"View"];
NSMutableDictionary *topLevel = [NSMutableDictionary dictionary];
NSMutableDictionary *item1 = [NSMutableDictionary dictionary];
NSString *item1title = [NSString stringWithString:#"Title 1"];
NSMutableDictionary *item1children = [NSMutableDictionary dictionary];
// create children
NSString *item1child1 = [NSString stringWithString:#"item 1, child 1"];
NSMutableDictionary *item1child2 = [NSMutableDictionary dictionary];
NSString *item1child2title = [NSString stringWithString:#"Title 1-2"];
NSMutableDictionary *item1child2children = [NSMutableDictionary dictionary];
NSString *item1child2child1 = [NSString stringWithString:#"item 1, child 2, child 1"];
NSString *item1child2child2 = [NSString stringWithString:#"item 1, child 2, child 2"];
[item1child2 setObject:item1child2title forKey:#"Title"];
[item1child2children setObject:item1child2child1 forKey:#"item 1 child2 child 1"];
[item1child2children setObject:item1child2child2 forKey:#"item 1 child2 child 2"];
[item1child2 setObject:item1child2children forKey:#"children"];
// add children to dictionary
[item1children setObject:item1child1 forKey:#"item1 child1"];
[item1children setObject:item1child2 forKey:#"item1 child2"];
// add to item 1 dict
[item1 setObject:item1title forKey:#"Title"];
[item1 setObject:item1children forKey:#"children"];
NSMutableDictionary *item2 = [NSMutableDictionary dictionary];
NSString *item2title = [NSString stringWithString:#"Title"];
NSMutableDictionary *item2children = [NSMutableDictionary dictionary];
NSString *item2child1 = [NSString stringWithString:#"item 2, child 1"];
NSString *item2child2 = [NSString stringWithString:#"item 2, child 2"];
NSString *item2child3 = [NSString stringWithString:#"item 2, child 3"];
// add children to dictionary
[item2children setObject:item2child1 forKey:#"item2 child1"];
[item2children setObject:item2child2 forKey:#"item2 child2"];
[item2children setObject:item2child3 forKey:#"item2 child3"];
// add to item 2 dict
[item2 setObject:item2title forKey:#"Title"];
[item2 setObject:item2children forKey:#"children"];
[topLevel setObject:item1 forKey:#"Item 1"];
[topLevel setObject:item2 forKey:#"Item 2"];
first of .. super! thanks .. I really appreciate the explanation and code snippet.
Since you gave me such a good explanation I hope you don't mind me asking a couple more questions.
First, I did as you suggested and this is what I came up with :
(I used my original property list instead of the example this time so this is where the drilldown table gets his( or needs to get his ) treestructure).
http://img509.imageshack.us/img509/7523/picture2lsg.png
NSDictionary *root = [NSMutableDictionary dictionary];
NSDictionary *item1 = [NSDictionary dictionaryWithObject:[NSArray arrayWithObject:#"VirtuaGym Online"] forKey:[NSArray arrayWithObjects:#"Title"]];
NSDictionary *item2 = [NSDictionary dictionaryWithObject:[NSArray arrayWithObject:#"Do the training"] forKey:[NSArray arrayWithObjects:#"Title"]];
NSDictionary *item3 = ...
[root setObject:item1 forKey:#"Item 1"];
[root setObject:item2 forKey:#"Item 2"];
Also did some research and tried something else with some other input..
NSMutableArray *Rows = [NSMutableArray arrayWithCapacity: 1];
for (int i = 0; i < 4; ++i) {
NSMutableArray *theChildren = [NSMutableArray arrayWithCapacity: 1];
[theChildren addObject: [NSString stringWithFormat: #"tester %d", i]];
NSString *aTitle = [NSString stringWithFormat: #"Item %d", i];
NSDictionary *anItem = [NSDictionary dictionaryWithObjectsAndKeys: aTitle, #"Title", theChildren, #"Children"];
[Rows addObject: anItem];
}
NSDictionary *Root = [NSDictionary withObject: Rows andKey: #"Rows"];
I decided to just test both of these however it does what I want. It gives me a EXC_BAD_ACCESS error.
I was also wondering since I saw you using number in your code snippet, couldn't you also use NSString since that's what the plist uses.. could be totally of here of course
NSDictionary *item1 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:#"Screen J",[NSNumber numberWithInt:3],nil]
forKeys:[NSArray arrayWithObjects:#"Title",#"View",nil]];
and third a question is about my possible approach to my app.
I have an xml parser which saves certain information in different arrays.
I want to use this information for my drilldown UITableviews (infoFirstScreen[] infoSecondScreen[] infoThirdScreen[]).
The information provided has to be connected like the tree I showed you above.
This is the reason I wanted to build the dictionary in code so I can take the info from my arrays and insert it here.
My question do you think my approach is correct, wrong or is there a faster way?
again really appreciate the explanation ;)