ios 10 和 ios 9 中的 NSManagedObjectContext(核心数据)
NSManagedObjectContext in ios 10 and ios 9 (core data)
我有一个使用核心数据的应用程序,它同时支持 ios 9 ios 10.I 我正在使用 xcode 8.2.1 来开发这个项目。 AppDelegate 文件具有当应用程序在 ios 10 上运行时获取 ManagedObjectContext 的方法,但是,当应用程序在 ios 9 上运行时我如何获取它。我尝试 google 但没有太大帮助。任何帮助!
我用来获取 ManagedObjectContext 的代码在这里:
NSManagedObjectContext *context = ((AppDelegate*)[[UIApplication sharedApplication] delegate]).persistentContainer.viewContext;
NSPersistentContainer
仅在 iOS 10 及以后可用。如果您需要支持较低的系统,则不能使用它。您必须在没有 NSPersistentContainer
.
的情况下设置自己的核心数据堆栈
正如 Jon Rose 提到的,NSPersistentContainer
只能从 iOS 10 开始使用。
如果您仍然需要您的应用程序在以前的版本中工作,最好的解决方案是使用旧的核心数据堆栈,这里有一篇很棒的博客解释了两种方法之间的区别:Core Data in ios10
另一种解决方案是使用 swift 中的 #available
属性来执行核心数据堆栈或 NSPersistentContainer,这里有关于此的文档:Swift Attributes
如果您的应用同时支持 ios 9 和 ios 10,那么您可以使用 #available
属性来检查当前的 运行ning 版本和 运行相应地编码,因为 NSPersistentContainer
仅在 iOS 10 及以后可用。
在Swift3
// MARK: - Core Data Saving support
func saveContext () {
let coreDataFileName = "Use your core data file name"
if #available(iOS 10.0, *) {
let context = persistentContainer.viewContext
if context.hasChanges {
do {
try context.save()
} catch {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
let nserror = error as NSError
fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
}
}
}else {
if managedObjectContext.hasChanges {
do {
try managedObjectContext.save()
} catch let error as NSError {
print("Ops there was an error \(error.localizedDescription)")
abort()
}
}
}
}
// Applications default directory address
lazy var applicationDocumentsDirectory: NSURL = {
let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
return urls[urls.count-1] as NSURL
}()
lazy var managedObjectModel: NSManagedObjectModel = {
// 1
let modelURL = Bundle.main.url(forResource: coreDataFileName, withExtension: "momd")!
return NSManagedObjectModel(contentsOf: modelURL)!
}()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.appendingPathComponent("\(coreDataFileName).sqlite")
do {
// If your looking for any kind of migration then here is the time to pass it to the options
try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: nil)
} catch let error as NSError {
print("Ops there was an error \(error.localizedDescription)")
abort()
}
return coordinator
}()
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
var context = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
context.persistentStoreCoordinator = coordinator
return context
}()
在Objective-C
在AppDelegate.m
#pragma mark - Core Data Saving support
@synthesize managedObjectContext = _managedObjectContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;
@synthesize persistentContainer = _persistentContainer;
- (NSURL *)applicationDocumentsDirectory {
// The directory the application uses to store the Core Data store file. This code uses a directory named "Your Bundle Indentifier" in the application's documents directory.
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
- (NSManagedObjectModel *)managedObjectModel {
// The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Use your core data file name" withExtension:@"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
// The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it.
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
// Create the coordinator and store
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Use your core data file name.sqlite"];
NSError *error = nil;
NSString *failureReason = @"There was an error creating or loading the application's saved data.";
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
// Report any error we got.
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
dict[NSLocalizedDescriptionKey] = @"Failed to initialize the application's saved data";
dict[NSLocalizedFailureReasonErrorKey] = failureReason;
dict[NSUnderlyingErrorKey] = error;
error = [NSError errorWithDomain:@"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
- (NSManagedObjectContext *)managedObjectContext {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (!coordinator) {
return nil;
}
_managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
return _managedObjectContext;
}
#pragma mark - Core Data Saving support
- (void)saveContext {
//Check current version.
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 10.0){
NSManagedObjectContext *context =_persistentContainer.viewContext;
if (context != nil) {
NSError *error = nil;
if ([context hasChanges] && ![context save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
}else{
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
NSError *error = nil;
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
}
}
在AppDelegate.h中使用
#pragma mark - Core data for messages vriable
@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
@property (readonly, strong) NSPersistentContainer *persistentContainer;
- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;
我有一个使用核心数据的应用程序,它同时支持 ios 9 ios 10.I 我正在使用 xcode 8.2.1 来开发这个项目。 AppDelegate 文件具有当应用程序在 ios 10 上运行时获取 ManagedObjectContext 的方法,但是,当应用程序在 ios 9 上运行时我如何获取它。我尝试 google 但没有太大帮助。任何帮助!
我用来获取 ManagedObjectContext 的代码在这里:
NSManagedObjectContext *context = ((AppDelegate*)[[UIApplication sharedApplication] delegate]).persistentContainer.viewContext;
NSPersistentContainer
仅在 iOS 10 及以后可用。如果您需要支持较低的系统,则不能使用它。您必须在没有 NSPersistentContainer
.
正如 Jon Rose 提到的,NSPersistentContainer
只能从 iOS 10 开始使用。
如果您仍然需要您的应用程序在以前的版本中工作,最好的解决方案是使用旧的核心数据堆栈,这里有一篇很棒的博客解释了两种方法之间的区别:Core Data in ios10
另一种解决方案是使用 swift 中的 #available
属性来执行核心数据堆栈或 NSPersistentContainer,这里有关于此的文档:Swift Attributes
如果您的应用同时支持 ios 9 和 ios 10,那么您可以使用 #available
属性来检查当前的 运行ning 版本和 运行相应地编码,因为 NSPersistentContainer
仅在 iOS 10 及以后可用。
在Swift3
// MARK: - Core Data Saving support
func saveContext () {
let coreDataFileName = "Use your core data file name"
if #available(iOS 10.0, *) {
let context = persistentContainer.viewContext
if context.hasChanges {
do {
try context.save()
} catch {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
let nserror = error as NSError
fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
}
}
}else {
if managedObjectContext.hasChanges {
do {
try managedObjectContext.save()
} catch let error as NSError {
print("Ops there was an error \(error.localizedDescription)")
abort()
}
}
}
}
// Applications default directory address
lazy var applicationDocumentsDirectory: NSURL = {
let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
return urls[urls.count-1] as NSURL
}()
lazy var managedObjectModel: NSManagedObjectModel = {
// 1
let modelURL = Bundle.main.url(forResource: coreDataFileName, withExtension: "momd")!
return NSManagedObjectModel(contentsOf: modelURL)!
}()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.appendingPathComponent("\(coreDataFileName).sqlite")
do {
// If your looking for any kind of migration then here is the time to pass it to the options
try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: nil)
} catch let error as NSError {
print("Ops there was an error \(error.localizedDescription)")
abort()
}
return coordinator
}()
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
var context = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
context.persistentStoreCoordinator = coordinator
return context
}()
在Objective-C 在AppDelegate.m
#pragma mark - Core Data Saving support
@synthesize managedObjectContext = _managedObjectContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;
@synthesize persistentContainer = _persistentContainer;
- (NSURL *)applicationDocumentsDirectory {
// The directory the application uses to store the Core Data store file. This code uses a directory named "Your Bundle Indentifier" in the application's documents directory.
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
- (NSManagedObjectModel *)managedObjectModel {
// The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Use your core data file name" withExtension:@"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
// The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it.
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
// Create the coordinator and store
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Use your core data file name.sqlite"];
NSError *error = nil;
NSString *failureReason = @"There was an error creating or loading the application's saved data.";
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
// Report any error we got.
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
dict[NSLocalizedDescriptionKey] = @"Failed to initialize the application's saved data";
dict[NSLocalizedFailureReasonErrorKey] = failureReason;
dict[NSUnderlyingErrorKey] = error;
error = [NSError errorWithDomain:@"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
- (NSManagedObjectContext *)managedObjectContext {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (!coordinator) {
return nil;
}
_managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
return _managedObjectContext;
}
#pragma mark - Core Data Saving support
- (void)saveContext {
//Check current version.
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 10.0){
NSManagedObjectContext *context =_persistentContainer.viewContext;
if (context != nil) {
NSError *error = nil;
if ([context hasChanges] && ![context save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
}else{
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
NSError *error = nil;
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
}
}
在AppDelegate.h中使用
#pragma mark - Core data for messages vriable
@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
@property (readonly, strong) NSPersistentContainer *persistentContainer;
- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;