Swift 2: Call can launch, but it is not marked with 'try' and the error is not handled

advertisements

After I installed Xcode 7 beta and convert my swift code to Swift 2, I got some issue with the code that I can't figure out. I know Swift 2 is new so I search and figure out since there is nothing about it, I should write a question.

Here is the error:

Call can throw, but it is not marked with 'try' and the error is not handled

Code:

func deleteAccountDetail(){
        let entityDescription = NSEntityDescription.entityForName("AccountDetail", inManagedObjectContext: Context!)
        let request = NSFetchRequest()
        request.entity = entityDescription

        //The Line Below is where i expect the error
        let fetchedEntities = self.Context!.executeFetchRequest(request) as! [AccountDetail]

        for entity in fetchedEntities {
        self.Context!.deleteObject(entity)
        }

        do {
            try self.Context!.save()
        } catch _ {
        }

    }

Snapshot:


You have to catch the error just as you're already doing for your save() call and since you're handling multiple errors here, you can try multiple calls sequentially in a single do-catch block, like so:

func deleteAccountDetail() {
    let entityDescription = NSEntityDescription.entityForName("AccountDetail", inManagedObjectContext: Context!)
    let request = NSFetchRequest()
    request.entity = entityDescription

    do {
        let fetchedEntities = try self.Context!.executeFetchRequest(request) as! [AccountDetail]

        for entity in fetchedEntities {
            self.Context!.deleteObject(entity)
        }

        try self.Context!.save()
    } catch {
        print(error)
    }
}

Or as @bames53 pointed out in the comments below, it is often better practice not to catch the error where it was thrown. You can mark the method as throws then try to call the method. For example:

func deleteAccountDetail() throws {
    let entityDescription = NSEntityDescription.entityForName("AccountDetail", inManagedObjectContext: Context!)
    let request = NSFetchRequest()

    request.entity = entityDescription

    let fetchedEntities = try Context.executeFetchRequest(request) as! [AccountDetail]

    for entity in fetchedEntities {
        self.Context!.deleteObject(entity)
    }

    try self.Context!.save()
}