NSPersistentContainer is only available in 10.0 or

问题:

It's because My deployment target is less than 10.

how to resolve for deployment target lower to 10.0 ?

回答1:

One of solutions is to use https://github.com/inspace-io/INSPersistentContainer

and add

typealias NSPersistentContainer         = INSPersistentContainer
typealias NSPersistentStoreDescription  = INSPersistentStoreDescription

to your file where you want to use

回答2:

Not available means not available.

There are two options:

• Use only the old NSPersistentStoreCoordinator / NSManagedObjectModel pattern.
• Use both patterns and write the code with availability checking if #available(iOS 10, *)

回答3:

Before iOS 10

you could access the NSManagedObjectContext directly from AppDelegate.h

lazy var managedObjectContext: NSManagedObjectContext? = {
// Returns the managed object context for the application (which is already bound to the persistent store
// coordinator for the application.) This property is optional since there are legitimate error
// conditions that could cause the creation of the context to fail.
let coordinator = self.persistentStoreCoordinator
if coordinator == nil {
    return nil
}
var managedObjectContext = NSManagedObjectContext()
managedObjectContext.persistentStoreCoordinator = coordinator
return managedObjectContext

(Original code)

from iOS 10 and newer

this changed and the NSManagedObjectContext has been moved into the PersistentContainer into the attribute viewContext

lazy var persistentContainer: NSPersistentContainer = {
/*
 The persistent container for the application. This implementation
 creates and returns a container, having loaded the store for the
 application to it. This property is optional since there are legitimate
 error conditions that could cause the creation of the store to fail.
*/
let container = NSPersistentContainer(name: "")
...
...

(original code)

So, you need to distinguish which version you're app is running on and then call the correct function. ManagedObjectContext inside AppDelegate or The ManagedObjectContext inside [PersistentContainer viewContext].

btw: Be careful with tutorials for versions before iOS 10.

回答4:

Use the @available tag like this: @available(iOS 10.0, *) lazy var persistentContainer: NSPersistentContainer = ...