How to use Transformable in Core Data?
To implement a Transformable attribute, configure it by setting its type to Transformable and specifying the transformer and custom class name in Data Model Inspector, then register a transformer with code before an app loads its Core Data stack.
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 transformable type in Core Data?
Core Data supports entity attributes of ‘Transformable’ type. Transformable type allows us to store custom data types as an object of the declared attribute for a record of an Entity. The only requirement is that our custom type should conform to NSCoding or we need to provide a custom value transformer.
What iOS predicate?
iOS Predicate String Strategy Predicate Format Strings are a typical Apple dev thing, and they also work in iOS. Predicate format strings enable basic comparisons and matching. In our case, they allow basic matching of elements according to simple criteria.
What is the predicate example?
A predicate is the part of a sentence, or a clause, that tells what the subject is doing or what the subject is. Let’s take the same sentence from before: “The cat is sleeping in the sun.” The clause sleeping in the sun is the predicate; it’s dictating what the cat is doing. Cute!
What is core data in Salesforce?
Core Data provides different attributes, including those common for all databases, such as Date or Decimal type, and non-standard attributes handled with Transformable type. It also provides Transient and Derived attributes so apps can derive one piece of data from the other.
What is the difference between Transformers in nssecureunarchivefromdata and core data?
Core Data requires the transformer be NSSecureUnarchiveFromData or its subclass, and that its transformedValue (_:) method converts a Data object to an instance of the custom class specified in Data Model Inspector and that reverseTransformedValue (_:) does the opposite – converts an instance of the custom class to a Data object.
What are the different types of core data?
Many apps need to persist and present different kinds of information. Core Data provides different attributes, including those common for all databases, such as Date or Decimal type, and non-standard attributes handled with Transformable type. It also provides Transient and Derived attributes so apps can derive one piece of data from the other.
What is a date in core data?
In a Core Data store, a Date attribute is a double value that represents a number of seconds since 1970. Using a variety of calendars, time zones, and locales, an app can convert a Date value to different date strings, or convert a date string to different Date values.