What is NSPredicate in swift?

NSPredicate is a Foundation class that specifies how data should be fetched or filtered. Its query language, which is like a cross between a SQL WHERE clause and a regular expression, provides an expressive, natural language interface to define logical conditions on which a collection is searched.

What is predicate in Core Data?

Core Data fetch requests can use predicates in SwiftUI just like they can with UIKit, all by providing a predicate property to your @FetchRequest property wrapper. Once that’s done, you can create a fetch request for one of your entities, passing in one or more sort descriptors and a predicate.

Which is an example of a format string in nspredicate?

Although it’s common to create predicates directly from instances of NSComparisonPredicate, NSCompoundPredicate, and NSExpression, you often create predicates from a format string which is parsed by the class methods on NSPredicate. Examples of predicate format strings include: Simple comparisons, such as grade == “7” or firstName like “Shaffiq”

How do you create a predicate in nspredicate?

Predicates represent logical conditions, which you can use to filter collections of objects. Although it’s common to create predicates directly from instances of NSComparisonPredicate, NSCompoundPredicate, and NSExpression, you often create predicates from a format string which is parsed by the class methods on NSPredicate.

Where to put the comparison symbol in nspredicate?

For case insensitive comparison, put [c] after the comparison symbol. As it is relatively time consuming for the app to parse the format string of the NSPredicate, we should try to reduce creating multiple NSPredicate and reuse similar NSPredicate as much as possible.

How to use nspredicate to fix a bug in Swift?

commitPredicate = NSPredicate(format: “message == ‘I fixed a bug in Swift'”) That means “make sure the message attribute is equal to this exact string.”. Typing an exact string like that is OK because you know what you’re doing, but please don’t ever use string interpolation to inject user values into a predicate.