写在前面,由于苹果公司对CoreData的改动，使得在Xcode8.0和ios10.0以上环境下使用新语法使用CoreData不兼容ios9以下系统，本实例主要简单介绍Swift3.0中CoreData的使用，同时处理了不兼容ios9以下版本系统的问题。
开发环境：Xcode8.1，iOS10.0
说明：本实例为swift纯代码编写
下面为实例的主要实现代码：
AppDelegate.swift
import UIKit
import CoreData
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
//创建导航视图为主界面
window = UIWindow(frame:UIScreen.main.bounds);
window?.backgroundColor = UIColor.white;
let nav = UINavigationController(rootViewController: ViewController());
window?.rootViewController = nav;
window?.makeKeyAndVisible();
return true
}
//省略......
func applicationWillTerminate(_ application: UIApplication) {
if #available(iOS 10.0, *) {
self.saveContext()
} else {
}
}
// MARK: - Core Data stack
@available(iOS 10.0 , *)
lazy var persistentContainer: NSPersistentContainer = {
let container = NSPersistentContainer(name: "saveDataDemo")
container.loadPersistentStores(completionHandler: { (storeDescription, error) in
if let error = error as NSError? {
fatalError("Unresolved error \(error), \(error.userInfo)")
}
})
return container
}()
lazy var applicationDocumentsDirectory: URL = {
let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
return urls[urls.count-1]
}()
//iOS9下的 Core Data stack
lazy var managedObjectModel: NSManagedObjectModel = {
let modelURL = Bundle.main.url(forResource: "saveDataDemo", withExtension: "momd")!
return NSManagedObjectModel(contentsOf: modelURL)!
}()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.appendingPathComponent("SingleViewCoreData.sqlite")
var failureReason = "There was an error creating or loading the application's saved data."
do {
try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: nil)
} catch {
// Report any error we got.
var dict = [String: AnyObject]()
dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject?
dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject?
dict[NSUnderlyingErrorKey] = error as NSError
let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
abort()
}
return coordinator
}()
lazy var managedObjectContext: NSManagedObjectContext = {
let coordinator = self.persistentStoreCoordinator
var managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
managedObjectContext.persistentStoreCoordinator = coordinator
return managedObjectContext
}()
//iOS9下的 Core Data stack结束
// MARK: - Core Data Saving support
@available(iOS 10.0 , *)
func saveContext () {
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)")
}
}
}
}
ViewController.swift
import UIKit
import CoreData
class ViewController: UIViewController , UITextFieldDelegate{
var mycontext : NSManagedObjectContext!;
var mynum , myname , myage : UITextField!;
override func viewDidLoad() {
if #available(iOS 10.0, *) {
mycontext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
} else {
print("IOS9");
mycontext = (UIApplication.shared.delegate as! AppDelegate).managedObjectContext
}
super.viewDidLoad()
//此处省略界面创建代码详细请看源文件
//添加事件实现隐藏键盘
let tap = UITapGestureRecognizer(target: self, action: #selector(tap(G:)));
self.view.addGestureRecognizer(tap);
}
//界面跳转
func showData(){
navigationController?.pushViewController(showViewController(), animated: true);
}
//隐藏键盘
func tap(G:UITapGestureRecognizer) {
self.view.endEditing(true);
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
self.view.endEditing(true);
return true;
}
//保存数据到CoreData
func SavaDataToCoredata(){
do{
let inserInfo = NSEntityDescription.insertNewObject(forEntityName: "MyStudents", into: mycontext);
if(mynum.text != "" && myname.text != "" && myage.text != ""){
inserInfo.setValue(Int(mynum.text!), forKey: "num");
inserInfo.setValue("\(myname.text!)", forKey: "name");
inserInfo.setValue(Int(myage.text!), forKey: "age");
try mycontext.save()
mynum.text = "";
myname.text = "";
myage.text = "";
let myAlert = UIAlertController(title: "提示", message: "保存成功", preferredStyle: .alert);
let myokAction = UIAlertAction(title: "确定", style: .default, handler: nil);
myAlert.addAction(myokAction);
self.present(myAlert, animated: true, completion: nil);
}else{
let myAlert = UIAlertController(title: "提示", message: "请输入完整的信息", preferredStyle: .alert);
let myOkAction = UIAlertAction(title: "确定", style: .default, handler: nil);
myAlert.addAction(myOkAction);
self.present(myAlert, animated: true, completion: nil);
}
}catch{
fatalError();
}
}
//清除coreData中的数据
func delCoreData(){
let request = NSFetchRequest<NSFetchRequestResult>(entityName: "MyStudents");
do{
let rels = try mycontext.fetch(request) as! [NSManagedObject];
for rel in rels{
mycontext.delete(rel);
}
try mycontext.save();
let myAlert = UIAlertController(title: "提示", message: "清空数据库成功", preferredStyle: .alert);
let myOkAction = UIAlertAction(title: "确定", style: .default, handler: nil);
myAlert.addAction(myOkAction);
present(myAlert, animated: true, completion: nil);
}catch{
fatalError();
}
}
}
showViewController.swift
import UIKit;
import CoreData;
class showViewController: UIViewController {
let fullsize = UIScreen.main.bounds.size;
let myEntity = "Students";
var myContext : NSManagedObjectContext!;
let request = NSFetchRequest<NSFetchRequestResult>(entityName: "MyStudents");
var myTextView : UITextView!;
override func viewDidLoad() {
if #available(iOS 10.0, *) {
myContext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
} else {
myContext = (UIApplication.shared.delegate as! AppDelegate).managedObjectContext
}
super.viewDidLoad()
self.title = "显示数据";
self.view.backgroundColor = UIColor.white;
myTextView = UITextView(frame: CGRect(x: 0, y: 0, width: fullsize.width, height: fullsize.height));
myTextView.center = CGPoint(x: fullsize.width * 0.5, y: fullsize.height * 0.5);
myTextView.textAlignment = .left;
myTextView.textColor = UIColor.red;
myTextView.isEditable = false;
self.view.addSubview(myTextView);
show();
}
func show(){
do{
let rels = try myContext.fetch(request) as! [NSManagedObject];
var re = "";
for rel in rels {
if rel.value(forKey: "name") != nil{
re += "\n学号：000\(rel.value(forKey: "num")!)\n" + "姓名： \(rel.value(forKey: "name")!)\n" + "年龄： \(rel.value(forKey: "age")!)\n";
}
}
if re != ""{
myTextView.text = re;
}else{
myTextView.text = "未找到相关数据！";
myTextView.textColor = UIColor.red;
}
}catch{
fatalError();
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
下面是程序运行效果图
未命名.png
