What is an NSPredicate?

What is an NSPredicate?

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 NSPredicate in Swift?

A definition of logical conditions for constraining a search for a fetch or for in-memory filtering. iOS 3.0+

How do you write NSPredicate in Swift?

In Swift, constructors skip the “blahWith…” part and just use the class name as a function and then go straight to the arguments, so [NSPredicate predicateWithFormat: …] would become NSPredicate(format: …) . (For another example, [NSArray arrayWithObject: …] would become NSArray(object: …) .

What is NSPredicate in Objective C?

CONTAINS operator : It allows to filter objects with matching subset. NSPredicate *filterByName = [NSPredicate predicateWithFormat:@”self. title CONTAINS[cd] %@”,@”Tom”]; LIKE : Its simple comparison filter. NSPredicate *filterByNameCIS = [NSPredicate predicateWithFormat:@”self.

Can’t use in contains operator with collection?

You’re getting this error because you’re trying to use a CONTAINS predicate on SearchResult objects, which aren’t collections with a defined notion of CONTAINS . This error occurs at runtime because NSPredicate parses and processes its string at runtime.

What are the types of predicate?

Predicates can be divided into two main categories: action and state of being. Predicates that describe an action can be simple, compound, or complete. A simple predicate is a verb or verb phrase without any modifiers or objects.

What is flatMap in IOS Swift?

Flatmap is used to flatten a collection of collections . But before flattening the collection, we can apply map to each elements. Apple docs says: Returns an array containing the concatenated results of calling the given transformation with each element of this sequence. Read it like : map + (Flat the collection)

What is map Swift?

Swift version: 5.4. The map() method allows us to transform arrays (and indeed any kind of collection) using a transformation closure we specify. The return value will be an array of the same size, containing your transformed elements.

Are iOS predicates usable in iOS 10?

NOTE: iOS predicates are usable in iOS 9.3 and below using the -ios uiautomation locator strategy and they are usable in iOS 10 and above using the -ios predicate string locator strategy It is worth looking at ‘-ios uiautomation’ search strategy with Predicates .

How do you evaluate a nspredicate object?

To evaluate a predicate, you use the NSPredicate method evaluateWithObject: and pass in the object against which the predicate will be evaluated. The method returns a Boolean value—in the following example, the result is YES.

How to use [nspredicate predicatewithformat] in Swift?

[NSPredicate predicateWithFormat:@”name contains[c] %@”, searchText]; In Swift, constructors skip the “blahWith…” part and just use the class name as a function and then go straight to the arguments, so [NSPredicate predicateWithFormat: …]would become NSPredicate(format: …).

How do you use predicates?

This document describes in general how you use predicates, and how the use of predicates may influence the structure of your application data. To evaluate a predicate, you use the NSPredicate method evaluateWithObject: and pass in the object against which the predicate will be evaluated.