In Swift 4 I have a CoreData "Sentence" model that has a String attribute "englishsentence". I also have an array of "words" and would like to fetch all sentences for which the "englishsentence" attribute contains one or more of the words in the array.
var words = ["today", "yesterday", "tomorrow"]
This array is just an example. It is supposed to change at runtime and can have any length.
and in the fetch request I am trying to do something like this:
let fetchRequest =
NSFetchRequest<NSManagedObject>(entityName: "Sentence")
let predicate = NSPredicate(format: "ANY englishsentence CONTAINS ANY word IN %@", words)
fetchRequest.predicate = predicate
I am able to create a predicate for all sentences that contain one particular word. However, I cannot get it to work with an array of words unless of course I iterate through the words-array and make a new fetch request for every single word. But this seems awfully inefficient.
One option would be to create a “compound predicate:”
let words = ["today", "yesterday", "tomorrow"]
let predicates = words.map {
NSPredicate(format: "englishsentence CONTAINS %@", $0)
}
let predicate = NSCompoundPredicate(orPredicateWithSubpredicates: predicates)
Another option is to match against a regular expression:
let regex = ".*(" + words.map {
NSRegularExpression.escapedPattern(for: $0)
}.joined(separator: "|") + ").*"
let predicate = NSPredicate(format: "englishsentence MATCHES %@", regex)
To match only “whole words” you can add the word boundary pattern \b
:
let regex = ".*\\b(" + words.map {
NSRegularExpression.escapedPattern(for: $0)
}.joined(separator: "|") + ")\\b.*"
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