I have an NSMutableDictionary (PerosnsListSections) and a class names Persons
NSMutableDictionary:
Keys are letters like "a,b,m ..."
Values are NSMutableArray
-> NSMutableArray have objects of class Persons
Persons class:
#property (assign,nonatomic) NSInteger pid;
#property (strong,nonatomic) NSString *name;
Now i have PerosnsListSections displayed in UITableView as shown in the image
what I want to achieve is when user types in the search bar first i have to filter the section which is the first letter then to filter the names under that section.
Sorry for my bad English (:
You can first select the correct array in the dictionary by doing:
NSString *firstLetter = [searchString substringWithRange:(NSRange){0,1}];
NSArray *people = PersonsListSection[firstLetter];
Then you can filter down on the people by using NSPredicates:
NSPredicate *namesBeginningWithKeyword = [NSPredicate predicateWithFormat:#"(name BEGINSWITH[cd] $letter)"];
NSArray *filteredPeople = [people filteredArrayUsingPredicate:[namesBeginningWithKeyword predicateWithSubstitutionVariables:#{#"letter": searchString}]]);
The question of how you make that be reflected in the tableview's content is a whole another question though.
Typically, you'll want your view controller to be the UISearchBar's delegate and react to change using the – (void)searchBar:textDidChange: delegate method.
There you could just call your tableview's - reloadData method so it tries recompute its content, calling all of its dataSource method like - numberOfSectionsInTableView: and so forth.
In these methods, in turn, you'll want to check whether some text was entered in the search bar and use the above tips to return the right sections/cells.
Related
I'm using the search bar to grab the text the user inputs and then use that to filter through an NSArray, and then assign the newly constructed array to the specified class' array property. Code below:
-(void)updateSearchResultsForSearchController:(UISearchController *)searchController{
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF beginswith[c] %#",searchController.searchBar.text];
NSArray *temp = [_array filteredArrayUsingPredicate:predicate];
_resultViewController.dynamicArray = temp;
}
But my resultViewController's tableView isn't displaying any data. However, if I use the below, it works:
-(void)updateSearchResultsForSearchController:(UISearchController *)searchController{
NSArray *temp = [[NSArray alloc]initWithObjects:#"hello",#"bye",#"why",#"okay", nil];
_resultViewController.dynamicArray = temp;
}
I'm not quite sure how to fix this problem. It seems like when I assign _resultViewController's dynamic array to temp, temp hasn't been set yet when working with filtering the array. But it works fine in the second case, so I know the rest of the code is right.
Thoughts?
Without knowing more about your _resultViewController.dynamicArray, it is impossible to help. Things to think about:
Is _resultViewController the view controller you think it is - the actual view controller whose view is being displayed?
Why would merely setting _resultViewController.dynamicArray cause anything to happen in that view controller? For example, in my own code, the view controller in question is usually a UITableViewController - and so, after setting its model array, I always call the table view's reloadData so that we actually see the filtered data.
I have an array - placeObjectsArray, that hold a lot of objects called place. Place is object of class PlaceHolder, in which i create different properties, filled with data:
self.place = [[PlaceHolder alloc]init];
// A lot of code here during parson XML with data
[self.placeObjectsArray addObject:self.place];
Header of this file look like this:
#interface PlaceHolder : NSObject
#property (strong, nonatomic) NSString *name;
#property (strong, nonatomic) NSString *description;
#property (strong, nonatomic) NSString *webPage;
It actually a container for an entity, each one hold data for name, description, image links etc. At now, i have array with place objects. What i want to, to manipulate with that objects inside an array. For example, how could i find all of data for specific "name"? (Name is one of properties in PlaceHolder class). How could i make an array that contain only names? How could i see in console 10 random "description"?
Any advice would be appreciated, thanks!
You're asking a bunch of separate questions.
First, how to select items in your array that match a particular name: Create an NSPredicate and use filteredArrayUsingPredicate. Google NSPredicate and you should find lots of examples.
Alternately you could use indexesOfObjectsPassingTest to get an index set of the items in the array that match your search criteria, and then use objectsAtIndexes: to turn the index set into a sub-array.
As for how to get all the names from the entries in your array, you can use a very cool trick in key value coding.
If you send an array the valueForKey message, it tries to fetch an item from each entry in the array using that key, and return them all in a new array. The code would look like this:
NSArray *names = [placeObjectsArray valueForKey #"name"];
Fetching 10 random descriptions is a little more complicated. You would need to write code that loops through the array, selecting 10 random items, and appends the description of each one into a new mutable array.
The trick there is to use arc4random_uniform to get a random index in your array:
NSUInteger random_index = arc4random_uniform(placeObjectsArray.count);
I leave the rest to you as a learning exercise.
If you want to fetch 10 random descriptions and make sure you never fetch the same description twice it's more complicated. You need to create a mutable copy of your array, then loop through the copy, fetching a random item, adding it's description to an array, and deleting the item from the array.
You can use NSPredicates:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF.name LIKE[cd] %#", nameSearch];
NSArray *filtered = [self.placeObjectsArray filteredArrayUsingPredicate:predicate];
You could iterate over your array looking for the PlaceHolder with a given name, like:
PlaceHolder *namedPlaceholder = nil;
for (PlaceHolder *placeholder in theArray) {
if ([placeholder.name isEqualToString:"whateverName"]) {
namedPlaceholder = placeholder;
break;
}
}
If you want to find PlaceHolders by name efficiently you might consider using a dictionary instead of an array. With a dictionary you can map names to objects, like:
NSMutableDictionary *myDictionary = [[NSMutableDictionary alloc] init];
myDictionary[#"foo"] = somePlaceholder;
myDictionary[#"bar"] = someOtherPlaceholder;
and retrieve them like:
PlaceHolder *somePlaceholder = myDictionary[#"foo"];
To get random objects from an array, I recommend getting random indexes using arc4random_uniform. This gives pseudo-random numbers with a better uniform distribution than rand or random, and does not require you to explicitly seed the sequence with srand or srandom.
PlaceHolder *randomPlaceholder = theArray[arc4random_uniform(theArray.count)];
or
const NSUInteger arrayCount = theArray.count;
for (NSUInteger j = 0; j < 10; j++) {
PlaceHolder *randomPlaceholder = theArray[arc4random_uniform(arrayCount)];
// Do something with randomPlaceholder.
}
I have an iOS app that pulls data from a server and persists it using CoreData. I have a UITableView that I am trying to populate with only select portions from a given core data attribute.
Before the table is populated I cycle through the data and pass what I want into a NSMutableArray. The problem is when I find an item I want it is not being added to the array.
I declare the array in my .h file like so...
#property (strong, nonatomic) NSMutableArray *theNewSource;
And Synthesize it in the .m file
#synthesize theNewSource = _theNewSource;
Here is the method...
-(NSMutableArray *)setDataSourceArray
{
for(int i = 0; i < rcount ; i++)
{
NSIndexPath *countingInteger = [NSIndexPath indexPathForItem:i inSection:0];
NSManagedObject *object = [self.fetchedResultsController objectAtIndexPath:countingInteger];
NSString *action = [object valueForKey:#"theActionName"];
if (![action isEqual:#"Login"])
{
[_theNewSource addObject:action];
}
}
NSLog(#"the array is now %#",_theNewSource);
return _theNewSource;
}
I've set a breakpoint in the line [_theNewSource addObject:action]. I can see in the console that the variable action does have a value but it is never added to _theNewSource array... I'm sure this is Objective C 101 but I can't get it figured out. Please Help!
Have you even created your _theNewSource array? It seems like you haven't done the following:
_theNewSource = [[NSMutableArray alloc] init];
Make sure you are creating your instance before trying to use it.
You should use a predicate in the NSFetchedResultsController's fetchRequest directly:
[NSPredicate predicateWithFormat:#"theActionName != %#", #"Login"];
NSFetchResultsControllers are particularly useful for driving table views and collection views, so filtering their results to create a separate data source is a code smell.
Doing it this way means that you can use the NSFetchedResultsController directly as the data source for your table instead of using it to create a filtered array to act as the datasource.
I'm new to iOS programming. I'm trying to bind the specific field from the objects in an array to a UITableView. Here's my code:
NSArray *personInfo; //contains a record with fields: name, address, email
personInfo = [[PersonDatabase database] getAllPersons]; //pulling the record into array
From there, I'm trying to get the field "name" from my array.
cell.textLabel.text = [NSString stringWithFormat:#"%#", [personInfo objectAtIndex: indexPath.row] retain]
As it seems you have objects in your array, what you may be looking for is the -[NSArray valueForKey:] method (documentation here).
For example:
NSArray *names = [personInfo valueForKey:#"name"];
This should return you an array containing all of the names in the array.
Are you trying to create a 2D Array?. If so you'll need to call objectAtIndex: twice on it in a nested call, but since you're new I'd suggest breaking down to a few lines so you can see more clearly what is happening.
Also, theres heaps of good code snippets on google for dealing with NSArray and table view.
Please check that if you delcare your array in #interface file as
//////.h
NSArray *personInfo;
#property(nonatomic ,retain) NSArray personInfo;
and then
in #implementation file
add this line
#synthesize personInfo;
hope it works
I am wondering what the correct way is to make a copy of an object defined in the app delegate or a singleton object. In short, I am making an app which requires a user to login. This login view is just a modal view controller on top of the 'real' app, which consists of a tabbarcontroller, plus some tableview controllers. After a successful login, there is send a data request to a remote server, and the modal view controller is dismissed, revealing the tabbar controller and table views holding the XML data. To parse the incoming data, I have created a singleton object named DataParser, which has interface
...
#interface DataParser : NSObject {
// Data objects that hold the data obtained from XML files
NSMutableDictionary *personnel;
NSMutableDictionary *schedule;
NSMutableDictionary *today;
}
#property (nonatomic, retain) NSMutableDictionary *personnel;
#property (nonatomic, retain) NSMutableDictionary *schedule;
#property (nonatomic, retain) NSMutableDictionary *today;
...
Now in these dictionaries I store (mutable) dictionaries and arrays holding NSString objects with the parsed XML data. Since I do not want to modify these original objects holding the parsed data (that is to say, I only want to modify them at the login stage, but not in any of the tableview controllers), I am creating a new dictionary object which holds a copy of the content of one of the dictionaries above in each tableview controller. So for instance, in the loadView of a view controller called ScheduleViewController I have
...
#interface ScheduleViewController : UITableViewController {
NSDictionary *copyOfSchedule;
}
#property (nonatomic, retain) NSDictionary *copyOfSchedule;
...
#end
#implementation ScheduleViewController
#synthesize copyOfSchedule;
- (void)loadView {
[super loadView];
DataParser *sharedSingleton = [DataParser sharedInstance];
self.copyOfSchedule = [NSDictionary dictionaryWithDictionary:sharedSingleton.schedule];
}
...
Now this seems to work fine. The only difficulty arises however, when the user 'logs out', which entails popping the login modal view controller back on the stack. When the user presses the login button again, then a new XML data request is send to the server and the dictionaries in the singleton object get refreshed with the (new) data (I check if they contain any data, if so I call removeAllObjects before filling them up again with newly parsed data). At this point the dictionaries in all view controllers should be updated too, however I am not quite sure how to go about this the right way. I have noticed that loadView is not always called again in this case and so to this end I have added the same code as above in loadView to every viewWillAppear method. After navigating back and forth between the different views or navigating back and forth between child views of a tableview a couple of times, I receive an EXC_BAD_ACCESS error however. I suspect this has to do with not properly retaining the copies of the original dictionaries, but I don't seem to be able to find a solution around this. Instead of using dictionaryWithDictionary, which I suspect is not the right way to go anyway, I also tried a different approach, where instead of using objects of type NSDictionary in ScheduleViewController I use NSMutableDictionary. So:
...
#interface ScheduleViewController : UITableViewController {
NSMutableDictionary *copyOfSchedule;
}
#property (nonatomic, retain) NSMutableDictionary *copyOfSchedule;
...
#end
#implementation ScheduleViewController
#synthesize copyOfSchedule;
- (void)loadView {
[super loadView];
DataParser *sharedSingleton = [DataParser sharedInstance];
self.copyOfSchedule = [[NSMutableDictionary alloc] initWithDictionary:sharedSingleton.schedule];
}
- (void)viewWillAppear {
DataParser *sharedSingleton = [DataParser sharedInstance];
[self.copyOfSchedule removeAllObjects];
[self.copyOfSchedule addEntriesFromDictionary:sharedSingleton.schedule];
[self.tableView reloadData];
}
...
But this doesn't get rid of the EXC_BAD_ACCESS errors. To make a very long story short: what would be the best way to go about making independent copies of objects defined in a singleton object or app delegate and which can be dynamically updated at request? Since I am already rather into the project and lots is going on, I realize that my question may be a bit vague. Nonetheless I hope there is somebody who could enlighten me somehow.
Deep copies are often made recursively. One way to do it would be to add -deepCopy methods to NSDictionary and NSArray. The dictionary version might go like this:
- (NSDictionary*)deepCopy
{
NSMutableDictionary *temp = [self mutableCopy];
for (id key in temp) {
id item = [temp objectForKey:key];
if ([item respondsToSelector:#sel(deepCopy)] {
// handle deep-copyable items, i.e. dictionaries and arrays
[temp setObject:[item deepCopy] forKey:key]
}
else if ([item respondsToSelector:#(copy)]) {
// most data objects implement NSCopyable, so will be handled here
[temp setObject:[item copy] forKey:key];
}
else {
// handle un-copyable items here, maybe throw an exception
}
}
NSDictionary *newDict = [[temp copy] autorelease];
[temp release]
return newDict;
}
I haven't tested that, so be a little careful. You'll want to do something similar for NSArray.
Note that views are not copyable.
It is quite a typical pattern that you build an array or dictionary with some code, so clearly it must be mutable while you add bits to it, and when you're done you don't want it ever to change. To do this:
Have a property like
#property (...) NSArray* myArray;
When you calculate the contents of myArray, use a mutable array to build it, like
NSMutableArray* myMutableArray = [NSMutableArray array];
When you're done building the array, just use
self.myArray = [NSArray arrayWithArry:myMutableArray];