Searching an Array for a value - objective-c

I have an array with this values:
(
(
John,
"John.plist",
active
),
(
Lucas,
"Lucas.plist",
inactive
)
)
What I need is to get the index of the active node.
Here's my code:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"%#",#"active"];
NSArray *results = [accounts filteredArrayUsingPredicate:predicate];
NSLog(#"%#", results);
And it's giving me error. What's wrong? thanks!

One way to solve this problem would be something like this:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"%# in self",#"active"];
NSArray *results = [accounts filteredArrayUsingPredicate:predicate];
NSLog(#"%#", results);
although a better solution would be dictionaries with key/value pairs instead of single strings

Related

Use NSPredicate to filter by index

Basically, what I want to do is this:
NSArray *objectsAtIndex1 = #[[#[#"Foo", #"Bar"] objectAtIndex:1]];
but using NSPredicate instead, so it would look something like this (however this is not working):
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF[1] != null"]
NSArray *objectsAtIndex1 = [#[#"Foo", #"Bar"] filteredArrayUsingPredicate:predicate]
And of course, #"Foo" and #"Bar" are in reality unknown values (and could even be dictionaries or numbers). Is it possible to achieve this?
I solved it by using the predicateWithBlock: method on NSPredicate like this:
NSArray *fooBarArray = #[#"Foo", #"Bar"];
NSUInteger index = 1;
NSPredicate *predicate = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
return [fooBarArray indexOfObject:evaluatedObject] == index;
}];
NSArray *objectsAtIndex1 = [fooBarArray filteredArrayUsingPredicate:predicate];
One caveat is however that the objects in fooBar-array needs to be unique for this to work, which is not perfect.

NSPredicate, search in a NSArray, inside a NSArray of NSDict

I have a NSArray of NSDictionary.
One of the keys of the NSDictionary contains a NSArray of strings.
Is there a way that I can use NSPredicate to find a specific strins in that Array of strings?
Thanks :)
Also: This work great, but not for sublevelArray
predicate = [NSPredicate predicateWithFormat:#" %K LIKE[cd] %#", sKey, sLookForString];
Just replace LIKE with CONTAINS in your format string. For example, given this array:
NSArray *dogs = #[#{#"name" : #"Fido",
#"toys" : #[#"Ball", #"Kong"]},
#{#"name" : #"Rover",
#"toys" : #[#"Ball", #"Rope"]},
#{#"name" : #"Spot",
#"toys" : #[#"Rope", #"Kong"]}];
...the following predicate can be used obtain a filtered array containing only the dictionaries where the value for the key toy is an array that contains the string Kong.
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"%K CONTAINS[cd] %#", #"toys", #"Kong"];
On NSArray you can use filteredArrayUsingPredicate:, on NSDictionary use enumerateKeysAndObjectsUsingBlock: and then for each value do either a filteredArrayUsingPredicate: if it is an NSArray or you can use evaluateWithObject: using the predicate itself.
If you want to filter the array of dictionaries based on the array of strings, you can use -predicateWithBlock to filter the array, as shown in the code below:
- (NSArray *)filterArray:(NSArray *)array WithSearchString:(NSString *)searchString {
NSPredicate *predicate = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
NSDictionary *dictionary = (NSDictionary *)evaluatedObject;
NSArray *strings = [dictionary objectForKey:#"strings"];
return [strings containsObject:searchString];
}];
return [array filteredArrayUsingPredicate:predicate];
}

IN operator with NSPredicate and SBElementArray

Does the IN operator work for filtering SBElementArrays? I have been trying to use it but it always returns a NULL array.
My code (hexArray will typically have more elements):
SBElementArray *musicTracks = [libraryPlaylist fileTracks];
hexArray = [NSArray arrayWithObject: #"3802BF81BD1DAB10"];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"ANY %K IN %#",#"persistentID",hexArray];
NSLog(#"%#", [[musicTracks filteredArrayUsingPredicate:predicate] valueForKey:#"persistentID"]);
NSLog(#"%#", hexArray);
NSLog(#"%#", predicate);
Output:
2013-05-26 12:59:29.907 test[1226:403] (null)
2013-05-26 12:59:29.907 test[1226:403] (3802BF81BD1DAB10)
2013-05-26 12:59:29.908 test[1226:403] ANY persistentID IN {"3802BF81BD1DAB10"}
I have tried setting the predicate to:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"ANY %K == %#",#"persistentID",hexArray];
Output:
2013-05-26 13:03:04.629 test[1258:403] (3802BF81BD1DAB10)
2013-05-26 13:03:04.630 test[1258:403] (3802BF81BD1DAB10)
2013-05-26 13:03:04.630 test[1258:403] ANY persistentID == {"3802BF81BD1DAB10"}
And this works fine. But I would like the IN functionality.
Instead of doing
persistentID IN ('abc', 'abc', 'abc', ...)
you can do
persistentID == 'abc' OR persistentID == 'abc' OR ...
It seems to work pretty fast.
NSMutableArray *subPredicates = [NSMutableArray arrayWithCapacity:persistentIDs.count];
for (NSNumber *persistentID in persistentIDs) {
[subPredicates addObject:pred(#"persistentID == %#", persistentID.hexValue)];
}
NSPredicate *predicate = [NSCompoundPredicate orPredicateWithSubpredicates:subPredicates];
[tracks filterUsingPredicate:predicate];
NSLog(#"%ld", tracks.count);
Try using CONTAINS[c]
Ex:-
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"ANY %# CONTAINS[c] %k",hexArray, #"persistentID"];
I ended up just looping through all the elements of hexArray and using an equality predicate on each pass. Probably not the most efficient, but it works.
for (NSString *hexID in hexArray){
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"persistentID == %#",hexID];
iTunesTrack *track = [[musicTracks filteredArrayUsingPredicate:predicate] objectAtIndex:0];
[track duplicateTo:playlist];
}
Your predicate should be %K IN %# (without the ANY), if I understand your intention correctly (get all the tracks that have one of the IDs in the array).
For some reason, this doesn't work with SBElementArray, but you could simply convert it to a regular NSArray before applying the predicate (an NSSet should work too, and might be more efficient):
SBElementArray *musicTracks = [libraryPlaylist fileTracks];
NSArray *musicTracksArray = [NSArray arrayWithArray:musicTracks];
NSArray *hexArray = [NSArray arrayWithObjects: #"CE24B292556DB1BA", #"CE24B292556DB1F0", #"CE24B292556DB1C4", nil];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"%K IN %#", #"persistentID", hexArray];
NSLog(#"%#", [[musicTracksArray filteredArrayUsingPredicate:predicate] valueForKey:#"persistentID"]);
Scripting Bridge technically supports the IN operator, in that it will construct a properly-formed Apple event for it, but most applications don't understand it. The best workaround is the chained OR tests as suggested by NSAddict.

NSPredicate on array of arrays

I have an array, that when printed out looks like this:
(
(
databaseVersion,
13
),
(
lockedSetId,
100
)
)
Would it be possible to filter this using an NSPredicate (potentially by the index in the array). So something like: give me all rows where element 0 is 'databaseVersion'? I know that if I had an array of dictionaries I could do this with a predicate similar the one found here, but I found that when using dictionaries and storing a large amount of data, my memory consumption went up (from ~80mb to ~120mb), so if possible I would to keep the array. Any suggestions on how this might be done?
This can be done using "SELF[index]" in the predicate:
NSArray *array = #[
#[#"databaseVersion", #13],
#[#"lockedSetId", #100],
#[#"databaseVersion", #55],
#[#"foo", #"bar"]
];
NSPredicate *pred = [NSPredicate predicateWithFormat:#"SELF[0] == %#", #"databaseVersion"];
NSArray *filtered = [array filteredArrayUsingPredicate:pred];
NSLog(#"%#", filtered);
Output:
(
(
databaseVersion,
13
),
(
databaseVersion,
55
)
)
Or you can use a block-based predicate:
NSPredicate *pred = [NSPredicate predicateWithBlock:^BOOL(NSArray *elem, NSDictionary *bindings) {
return [elem[0] isEqualTo:#"databaseVersion"];
}];
Simply you can use ANY in NSPredicate:
it's works fine
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"ANY SELF == %#", #"value"];
or
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"ANY SELF contains[cd] %#", #"value"];

How to modify this predicate so it handles multiple keywords efficiently

I have this predicate:
NSPredicate * thePredicateKeyword = [NSPredicate predicateWithFormat:#"any keywords.thekeyword beginswith [cd] %#", searchTerm];
Basically each business have many to many relationship with keywords.
But suppose I do not have one searchTerm. Say I have an array.
How would I do so?
I suppose I can just make predicate for each and combine them with or predicate, etc.
However, is there a way to more efficiently do this using in keywords or stuff like that?
What about a function that returns something like this:
-(NSPredicate *)createCompoundPredicateForSearchTerms:(NSArray *)searchTerms
{
NSMutableArray *subPredicates = [[NSMutableArray alloc] init];
NSEnumerator *searchTermEnum = [searchTerms objectEnumerator];
NSString *searchTerm;
while (searchTerm = [searchTermEnum nextObject]) {
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"keywords.thekeyword beginswith [cd] %#", searchTerm];
[subPredicates addObject:predicate];
}
return [NSCompoundPredicate andPredicateWithSubpredicates:subPredicates];
}
This is what I actually use. However, the anwer I chose is what inspire it.
NSArray * keywords = [searchTerm componentsSeparatedByString:#" "];
NSMutableArray * keywordPredicates = [NSMutableArray array];
for (NSString * aKeyword in keywords) {
NSPredicate * thePredicateKeyword = [NSPredicate predicateWithFormat:#"any keywords.thekeyword beginswith [cd] %#", aKeyword];
[keywordPredicates addObject:thePredicateKeyword];
}
NSPredicate * thePredicateKeyword = [NSCompoundPredicate orPredicateWithSubpredicates:keywordPredicates];
return thePredicateKeyword;