CODEWITHSUNDEEP
swift
Magdalena Dziesińska
Magdalena Dziesińska

Reputation: 71

Value of type 'NSFetchRequest' has no member 'performFetch'

I write code 

    var fetchRequest: NSFetchRequest = NSFetchRequest(entityName: "Doctor")
    fetchRequest.predicate = NSPredicate(format: "id != nil")



let sortDescriptors: [NSSortDescriptor] = [(NSSortDescriptor.init(key: "distance", ascending: true)), (NSSortDescriptor.init(key: "lastname", ascending: true))]
fetchRequest.sortDescriptors = sortDescriptors

var error: NSError? = nil

// show error Value of type 'NSFetchRequest' has no member 'performFetch' 

var fetchSuccessful: Bool = fetchRequest.performFetch(error)

Upvotes: 0

Views: 866

Answers (3)

Alexander
Alexander

Reputation: 63369

What you're looking for is executeFetchRequest(_:) which throws rather than using taking an NSError param.

If the last non-block parameter of an Objective-C method is of type NSError **, Swift replaces it with the throws keyword, to indicate that the method can throw an error. If the Objective-C method’s error parameter is also its first parameter, Swift attempts to simplify the method name further, by removing the “WithError” or “AndReturnError” suffix, if present, from the first part of the selector. If another method is declared with the resulting selector, the method name is not changed. - Using Swift with Cocoa and Objective-C (Swift 2.2) - Error Handling

Upvotes: 0

devim1
devim1

Reputation: 532

@Magdalena Dziesińska: In your code...

var fetchSuccessful: Bool = fetchRequest.performFetch(error)

"performFetch" does not exist. To handle the error (error handling) place it within a 'do-try-catch statement' e.g. after your code...

 var fetchRequest: NSFetchRequest = NSFetchRequest(entityName: "Doctor")
fetchRequest.predicate = NSPredicate(format: "id != nil")

let sortDescriptors: [NSSortDescriptor] = [(NSSortDescriptor.init(key: "distance", ascending: true)), (NSSortDescriptor.init(key: "lastname", ascending: true))] fetchRequest.sortDescriptors = sortDescriptors

Use the following do-try-catch statement to catch any errors and get the fetch request.

do {
        let results = try context.executeFetchRequest(request)
    } catch {
        print("requesting error")
    }

nb: request is where you place your "fetchRequest"

Upvotes: 1

Yury
Yury

Reputation: 6114

You can not perform fetch request without context. If you have NSManagedObjectContext instance, you may use it executeFetchRequest(_:) method with your fetch request. More, if you have NSFetchedResultsController instance, initialized by your fetch request, you can use performFetch() method of this controller. You absolutely need to read more documentation of CoreData https://developer.apple.com/library/watchos/documentation/Cocoa/Conceptual/CoreData/index.html

Upvotes: 0

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