I am trying to work out how many cells my table view should have. This is determined by results of a query which are stored in Array.
When the view is loaded the array might not exist or have any values so the cells should be 0.
How do I check through my array to check for a specific object. I understand I can use containsObject or equalTo...
My array would consists of objects like this:
{<GameTurn:TLED0qH44P:(null)> {\n GameRef = \"<Game:KgguI4ig4O>\";\n GameTurnImage = \"<PFFile: 0xb3da9d0>\";\n GameTurnWord = tester;\n OriginalImageCenterX = \"27.9\";\n OriginalImageCenterY = \"29.39375\";\n TurnCount = 1;\n UploadedBy = \"<PFUser:UgkZDtDsVC>\";\n}
There would be multiple entries of the above. For each entry I need to check if the UploadedBy key is equal to the PFUser currentUser. If it is add one cell, and so on.
So I need to get an overall count of the items in the array where that key is equalto the current user.
You can filter the array to get a new array of all matching objects:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"UploadedBy = %#", currentUser];
NSArray *filtered = [array filteredArrayUsingPredicate:predicate];
and use the filtered array as table view data source.
If the array comes from a Core Data fetch request, it would be more effective to
add the predicate to the fetch request already.
There are many ways you can filter an array in Objective-C. Here is one method using blocks and NSIndexSet.
You can grab all the indexes of your original array where the objects pass a test, specified in the block. Then create another array consisting of the objects at those indexes.
// get all indexes of objects passing your test
NSIndexSet *indexes = [myArray indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
// replace this with your equality logic
return [obj uploadedBy] == [PFUser currentUser];
}];
// Filled with just objects passing your test
NSArray *passingObjects = [myArray objectsAtIndexes: indexes];
Related
I have an array of uids, and another array of objects. The objects structure is such that it has a name and a uid. I would like to search the array or objects, and return an array of those objects that match the uids from the first array. I was exploring using undersore.m but I'm not sure if this is appropriate.
Use a simple loop:
NSArray *uids = ... // your array of UIDs
NSArray *objects = ... // your array of objects with a name and uid
NSMutableArray *matches = [NSMutableArray array];
for (SomeClass *object in objects) {
if ([uids containsObject:object.uid]) {
[matches addObject:object];
}
}
matches will contain the matching objects.
Obviously you need to change SomeClass to your actual class that has the name and uid. And I'm assuming your class has a uid property. Adjust as needed.
I cannot find a way to get the nth item in an array using an NSPredicate string. For example:
//You cannot touch or modify the code inside this method. You can only use the predicate string param to filter the array.
- (NSArray *)filterUsingNSPredicate:(NSString *)PredicateString
{
NSArray *array = #[
#"firstItem",
#"secondItem",
#"thirdItem",
#"fourthItem",
];
NSPredicate *pred = [NSPredicate predicateWithFormat:PredicateString];
NSArray *filtered = [array filteredArrayUsingPredicate:pred];
NSLog(#"This is the second item in the array! %#",filtered); //Thats the only thing in the array.
return filtered;
}
If you want to get an item, you don't receive an NSArray, because you will only receive an object.
You can use NSPredicate to search by name of an object in your array. But what you say, that is not what you want.
You can use [array objectAtIndex:index];, that returns the object in the position you indicate in index.
If you want the index of an object, you can use [array indexOfObject:object];, that returns the index of the object.
Predicates don't know about array indexes. They only know about the single object that they're presented with at any one time, and whether that object makes the predicate true or false.
The way you're presenting this problem in the comments makes absolutely no sense. If you can get a filtered version of the array, then you can get the array. Here's how you use the method you show to do so:
NSArray * fullList = [theAPI filterUsingNSPredicate:#"TRUEPREDICATE"];
TRUEPREDICATE is a special value for predicate strings that always evaluates to true. When you filter an array with that predicate, the result will be identical to the original.
You now have a reference to the array, and can index into it as you would normally.
You can create predicate with block https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSPredicate_Class/#//apple_ref/occ/clm/NSPredicate/predicateWithBlock%3A like this to get 6-th element (at index 5 counting from 0):
__block NSInteger index = 0;
NSPredicate *pred = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary<NSString *, id> *bindings)(
return index++ == 5;
)];
I have a tableview that i want to search through with a searchable. It worked before but when i added sections i got into trouble because i had to change from arrays to dictionary.
So basically i have a NSDictionary that looks like this
{ #"districtA": array with point objects, #"districtB": array with point objects}
I need to filter them based on the point objects.name that is in the arrays. After that i want to create a new nsdictionary with the filtered objects in it.
I tried at least 10 different methods but i can't figure it out so i think this is the only way that i am most positive that should work.
This is the only way i can think of if there is an easier way or more logic way please tell me.
-(void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope {
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF.name BEGINSWITH[c] %#",searchText];
//create new array to fill
NSArray *arrayWithFilteredPoints = [[NSArray alloc] init];
//loop through the values and put into an rray based on the predicate
arrayWithFilteredPoints = [NSArray arrayWithObject:[[self.PointList allValues] filteredArrayUsingPredicate:predicate]];
NSMutableDictionary *dict = [#{} mutableCopy];
for (Point *point in arrayWithFilteredPoints) {
if (![dict objectForKey:Point.district])
dict[Point.district] = [#[] mutableCopy];
[dict[Point.district]addObject:Point];
}
self.filteredPointList = dict;
self.filteredDistrictSectionNames = [[dict allKeys] sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];}
This results in a crash, it happens of course where the predicate is used but i don't know how to debug what predicate i should use:
on 'NSInvalidArgumentException', reason: 'Can't do a substring operation with something that isn't a string (lhs = (
West ) rhs = w)'
I have read the comments and you are right. There was something wrong with my code.
I changed the logic, i added some more steps (like creating NSArray without needing it) to make the solution clear
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF.name BEGINSWITH[c] %#",searchText];
//1. create new array to fill only the Points from the dictionary
NSArray *allPoints = [self.PointList allValues];
NSMutableArray *allPointObjects = [[NSMutableArray alloc]init];
for (NSArray *array in allPoints) {
for (Point *point in array) {
[allPointObjects addObject:point];
}
}
//2. loop through allPointObjects and put into an mutablearray based on the predicate
NSArray *arrayWithFilteredPoints = [[NSArray alloc] init];
arrayWithFilteredPoints = [allPointObjects filteredArrayUsingPredicate:predicate];
NSMutableDictionary *dict = [#{} mutableCopy];
for (Point *point in arrayWithFilteredPoints) {
if (![dict objectForKey:point.district])
dict[point.district] = [#[] mutableCopy];
[dict[point.district]addObject:Point];
}
self.filteredPointList = dict;
self.filteredDistrictSectionNames = [[dict allKeys] sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];
I wanted a filtered nsdictionary at the end that i can pass back to my tableview that reads the dictionary objects based on the keys (districts)
It seems clear from your description that [self.PointList allValues] is not an array of Point objects but an array of arrays of Point objects. That is the source of your difficulty, including your original crash.
You need to decide what to do about that; for example, if you want just one big array of Point objects, then flatten the array of arrays before you filter. I can't advise you further because it is not obvious to me what ultimate outcome you desire.
EDIT You've now modified your code and I can see more clearly what you're trying to do. You have a dictionary whose values are arrays of points, and you are trying to filter some of the points out of each array. What I would have done is to do that - i.e., run thru the keys, extract each array, filter it, and put it back (or delete the key if the array is now empty). But I can see that what you are doing should work, because you have cleverly put the keys into the points to start with, so you can reconstruct the dictionary structure from that.
I have an NSArray and I need to get data from two keys and put together in a NSMutableDictionary. One key has stringvalues and the other NSNumbervalues. When I try to create NSCountedSetwithout adding the keys I want to use to separate arrays, it doesn't work, because the objects are not identical, basically, I need to check if objectId is identical, don't matter if the other keys are different.
Here is the initial code:
for (PFObject *objeto in objects) {
PFObject *exercicio = objeto[#"exercicio"];
NSString *string = exercicio.objectId;
NSNumber *nota = objeto[#"nota"];
[exercicios addObject:string];
[notas addObject:nota];
So I create two NSMutableArraysand store the values I need. When I logthe arrays after this, they are perfectly ordered, meaning the NSStringis in the same indexof the NSNumberit belongs to in the other array. So far, so good.
Now, when I create the NSCountedSetwith the strings, it changes the order.
NSCountedSet *countedExercicios = [[NSCountedSet alloc] initWithArray:exercicios];.
My goal is to sum the NSNumbers pertaining to an specific object, therefore, when the order changes, I lose the connection between the two arrays.
I'm not sure what I could do to solve this problem, or even if there's a different approach to achieve the result I need.
You can create NSDictionary and add it to array. You will have just one array and you won't lose the connection, you can use objectId as a key and NSNumber as a value:
for (PFObject *objeto in objects) {
PFObject *exercicio = objeto[#"exercicio"];
NSString *string = exercicio.objectId;
NSNumber *nota = objeto[#"nota"];
NSDictionary *dict = #{string: nota};
[newArray addObject: dict];
}
When you need get all key (objectId) you can use NSPredictate.
Hope this help
I want to display name and lastName in my UITableViewCell. I have an array with a lot of data that I retrieve from a database, and pretty much everything I need is in the array, the trick is to filter and show the results as I want.
I have the following code to filter what is being typed on searchBar and add to an NSMutableArray:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"usuario.username contains [cd] %#", searchText];
NSArray *filtroUsuario = [name filteredArrayUsingPredicate:predicate];
searchResults = [filtroUsuario valueForKeyPath:#"#distinctUnionOfObjects.usuario.nome"];
I use #distinctUnionOfObjects because the objects that I'm filtering are not user objects, therefore I want to retrieve user values, so as some objects point to the same user, I get duplicate names.
The code to put information on the UITableView is like this:
cell.textLabel.text = searchResults[indexPath.row];
It all works fine. My trouble is that now I want to show one more key on the cell, so the keypath would be usuario.sobrenome. How would I put both values together?
I've tried playing with the line:
searchResults = [filtroUsuario valueForKeyPath:#"#distinctUnionOfObjects.usuario.nome"];
and got some interesting results, but not the one I'm expecting.
It looks like you should be able to use #distinctUnionOfObjects.usuario, so your results is an array of user objects (or some other objects with the keys that you require). Then in the table view cell setup you do:
id user = searchResults[indexPath.row];
cell.textLabel.text = [user valueForKey:#"nome"];
cell.otherTextLabel.text = [user valueForKey:#"sobrenome"];