I have an NSArray of objects with properties such as firstName, lastName, clientID etc. and i would like to perform a search on the array based on a search keyword. This keyword must be checked against the first name and the last name properties and return a subset of the original array that contains only those objects whose first/last name contain the search term. Is there any efficient/fast way to do this?
As a second thought, I think -filteredArrayUsingPredicate: might be better for you.
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"%K = %#", #"firstName", #"Bob"];
NSArray *filteredArray = [array filteredArrayUsingPredicate:predicate];
This returns a sub-array of objects from the array that have the first name of "Bob".
I think your looking for -indexesOfObjectsPassingTest:
NSIndexSet *indexSet = [array indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
MyObject *myObject = (MyObject *)obj;
return [myObject.firstName isEqualToString:#"Bob"];
}];
This returns an index set of all the objects in the array with the first name of "Bob".
Another approach returning a new array containing only matching objects:
-(NSArray *)matchingClientsFromArray:(NSArray *)objects withFirstName:(NSString *)firstName andLastName:(NSString *)lastName{
NSMutableArray *objectArray = [NSMutableArray new];
for (Client *client in objectArray){
if ([client.firstName isEqualToString:firstName] &&
[client.lastName isEqualToString:lastName]) {
[objectArray addObject:client];
}
}
return [objectArray copy];
}
Related
My NSMutableArray contains some strings as elements. One of the element is repeated many times at different indexes in the array. For example [#"", #"1,2,3",#"",#"5,3,2,1",#""].
I want to remove all the elements with value #"" from the mutable array. I tried following ways but couldn't get the solution.
Using For loop:
for(id obj in myMutableArray)
{
if([obj isEqualToString:#""])
{
[myMytableArray removeObject:obj];
}
}
Using dummy mutable array called nextMutableArray
for(id obj in myMutableArray)
{
if([obj isEqualToString:#""])
{
continue;
}
else [nextMutableArray addObject:obj];
}
In both the ways, elements (#"") at other indexes are removed but not at the index 0 (first object). What could be the possible reason? Is there any way to remove all the elements that contain string #"" from the mutable array?
one option is to filter your array using predicates:
NSArray *someArray = #[#"", #"1,2,3", #"", #"5,3,2,1", #""];
NSLog(#"%#", someArray);
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF != ''"];
NSArray *filteredArray = [someArray filteredArrayUsingPredicate:predicate];
NSLog(#"%#", filteredArray);
No Need of For loop. Simply use this.
[mutableArray removeObjectIdenticalTo:#""];
If you want to remove duplicate entries from an array, You can use NSSet Class.
NSSet did not accept duplicate/s value.
NSMutableArray *arrTest=[[NSMutableArray alloc]initWithObjects:#"", #"1,2,3",#"",#"5,3,2,1",#"", nil];
NSSet *set = [NSSet setWithArray:arrTest];
arrTest = [[set allObjects] mutableCopy];
or
You can do like this:
NSPredicate *predicate = [NSPredicate predicateWithBlock:^BOOL(id str, NSDictionary *unused) { return ![str isEqualToString:#""]; }];
arrTest = [[arrTest filteredArrayUsingPredicate:predicate]mutableCopy];
This is fast and simple way.
I have two arrays and I'm trying to filter the first (array1) with a matching property that exists in a second array (array2). The first array is a dictionary array with key 'name'. The second array is an array of objects with property 'name'. Is it possible to filter contents of 'array1' and display only those that have a matching 'name' found in 'array2'?
I've tried:
NSPredicate *pred = [NSPredicate predicateWithFormat:#"name == #%",self.array2];
NSArray *results = [array1 filteredArrayUsingPredicate:pred];
NSLog(#"The results array is %#", results);
Rather than '==' I've tried a mix of 'IN' and '#K' and 'self' but it either crashes or results are 0.
NSPredicate *pred = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
return [[array2 valueForKey:#"name"] containsObject:[evaluatedObject objectForKey:#"name"]];
}];
This should work with IN:
NSArray *matchSet = [self.array2 valueForKey:#"name"];
NSPredicate *pred = [NSPredicate predicateWithFormat:#"name IN #%",matchSet];
Typed in Safari.
https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Predicates/Articles/pSyntax.html#//apple_ref/doc/uid/TP40001795-215891
Here's a quick example of how you could accomplish this:
int main(int argc, const char * argv[])
{
#autoreleasepool {
NSArray *arrayOne = #[#{#"name": #"Alvin"}, #{#"name": #"Brian"}, #{#"name": #"Charlie"}];
BMPPerson *alvin = [[BMPPerson alloc] initWithName:#"Alvin"];
BMPPerson *charlie = [[BMPPerson alloc] initWithName:#"Charlie"];
NSArray *arrayTwo = #[alvin, charlie];
NSArray *values = [arrayTwo valueForKey:#"name"];
NSMutableArray *filteredValues = [NSMutableArray array];
[arrayOne enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSString *name = [obj valueForKey:#"name"];
if ([values containsObject:name]) {
[filteredValues addObject:name];
}
}];
NSLog(#"%#", filteredValues);
}
return 0;
}
In the example, arrayOne is an NSArray of NSDictionary objects. Each object has a key of name.
The objects contained in arrayTwo are a basic NSObject subclass that has a name property.
To get the values of the name properties for all of the objects in arrayTwo we make use of the key-value coding method -valueForKey: which calls -valueForKey: on each object in the receiver and returns an array of the results.
We then create an NSMutableArray to hold the filtered results from arrayOne.
Next we enumerate the objects in arrayOne using the -enumerateObjectsUsingBlock: method. In this example, we know that the obj argument is an NSDictionary that has a key of name. Instead of casting to an NSDictionary and calling -objectForKey: we can simply call -valueForKey: and store the value in our local variable name. We then check to see if name is in the values array and if it is, add it to our filteredValues.
I've a person object which has NSString properties firstname, lastname, birthday, and NSMutableDictionary of different phone numbers of that person.
I've added different person objects in an NSMutableArray named personArray.
Try using this method on NSArray. Something like this:
return [personArray[[personArray indexOfObjectPassingTest:^ (id obj, NSUInteger index, BOOL stop) {
return [lastName isEqualToString:[obj lastName]];
}]] phoneNumber];
You get the idea.
You should be able to do it like this:
-(NSArray *) phoneNumberFor:(NSString *)lastName{
NSInteger indx = [self.personArray indexOfObjectPassingTest:^BOOL(Person *aPerson, NSUInteger idx, BOOL *stop) {
return [aPerson.lastname isEqualToString:lastName];
}];
if (indx != NSNotFound) {
return [self.personArray[indx] phoneNumbers].allValues;
}else{
return nil;
}
}
In this example, I'm assuming an array property called personArray, a class name of "Person" for your person objects, and a mutable dictionary called phoneNumbers. I'm also assuming that the dictionary contains several keys and values, where all of the values are phone numbers.
You can get object from array of the given lastname like as follow:-
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"lastname == '%#'", lastname];
NSArray *foundPersonArray = [personArray filteredArrayUsingPredicate:predicate];
NSLog("found person object = %#",foundPersonArray);
But if you want to search multiple object of same lastname from array then you can do following:-
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"lastname LIKE[c] %#", lastname];
NSArray *foundPersonArray = [personArray filteredArrayUsingPredicate:predicate];
NSLog("found person object = %#",foundPersonArray);
I have an NSArray with Store objects. Each Store object has two NSString objects; StoreID and Name.
I would like to check quickly if an ID exists in this NSArray with Store objects.
Example:
Store *s1 = [[Store alloc] init];
s1.name = #"Some Name";
s1.id = #"123ABC";
Store *s2 = [[Store alloc] init];
s2.name = #"Some Other Name";
s2.id = #"ABC123";
NSArray *array = [[NSArray alloc] initWithObjects:s1, s2, nil];
NSString *myIdOne = #"ABCDEF";
NSString *myIdTwo = #"123ABC";
BOOL myIdOneExists = ...?
BOOL myIdTwoExists = ...?
Its the ...? I need to figure out. I know I can do this using a for loop and break when found... but this seems to me like an nasty approach since the NSArray could contain thousands of objects,... theoretically.
So I would like to know about a better solution.
Here's the thing: No matter what solution you go with, it will more or less boil down to "loop over the array and return whether or not the object was found." There is no way to search an array more quickly than this unless very specific conditions are met (e.g. the array is already sorted by the value you're searching). You can use a predicate, you can use an enumerator, you can use fast enumeration or you can use a test block — under the hood, they all amount to "loop over the array and perform a test." That's just how arrays work.
If this is something you need to do often and performance is a problem with the naive solution, a sensible solution might be to cache your IDs in an NSSet. Sets are tuned for fast member detection, so you should be able to get your answer much more quickly than you could with an array.
My personal "loop-over-the-array" solution:
BOOL idExists = NSNotFound != [stores indexOfObjectPassingTest:^(Store *store, NSUInteger idx, BOOL *stop) {
return [store.id isEqualToString:#"whatever"];
}];
(Written in the browser, so, y'know, caveat compilor.)
Try this:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"%K == %#",#"id", myID];
NSArray *filteredArray = [array filteredArrayUsingPredicate:predicate];
if (filteredArray.count > 0)
Store *store = [filteredArray objectAtIndex:0];
Simplest solution, just use KVC:
NSArray *results = [array valueForKey:#"id"];
BOOL myIdOneExists = [results containsObject:myIdOne];
BOOL myIdTwoExists = [results containsObject:myIdTwo];
-(BOOL) id:(NSString*) theId existsInArray:(NSArray*) theArray {
for (Store* theStore in theArray) {
if ([theStore.id isEqualToString theId]) {
return YES;
}
}
return NO;
}
Another approach is to implement the isEqual method in Store to compare IDs only. Then construct a dummy Store object with the ID you're looking for and use indexOfObject or containsObject, referencing your dummy Store object.
I have a word list stored in an NSArray, I want to find all the words in it with the ending 'ing'.
Could someone please provide me with some sample/pseudo code.
Use NSPredicate to filter NSArrays.
NSArray *array = #[#"test", #"testing", #"check", #"checking"];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF ENDSWITH 'ing'"];
NSArray *filteredArray = [array filteredArrayUsingPredicate:predicate];
Let's say you have an array defined:
NSArray *wordList = // you have the contents defined properly
Then you can enumerate the array using a block
// This array will hold the results.
NSMutableArray *resultArray = [NSMutableArray new];
// Enumerate the wordlist with a block
[wordlist enumerateObjectsUsingBlock:(id obj, NSUInteger idx, BOOL *stop) {
if ([obj hasSuffix:#"ing"]) {
// Add the word to the result list
[result addObject:obj];
}
}];
// resultArray now has the words ending in "ing"
(I am using ARC in this code block)
I am giving an example using blocks because its gives you more options should you need them, and it's a more modern approach to enumerating collections. You could also do this with a concurrent enumeration and get some performance benefits as well.
Just loop through it and check the suffixes like that:
for (NSString *myString in myArray) {
if ([myString hasSuffix:#"ing"]){
// do something with myString which ends with "ing"
}
}
NSMutableArray *results = [[NSMutableArray alloc] init];
// assuming your array of words is called array:
for (int i = 0; i < [array count]; i++)
{
NSString *word = [array objectAtIndex: i];
if ([word hasSuffix: #"ing"])
[results addObject: word];
}
// do some processing
[results release]; // if you're not using ARC yet.
Typed from scratch, should work :)