// 1. 建立模型文件
// 2. 建立CoreDataStack
// 3. 設(shè)置AppDelegate

?

接著

// // CoreDataStack.swift // CoreDataStackDemo // // Created by wangbiao on 15/10/29. // Copyright ? 2015年 wangbiao. All rights reserved. // import CoreDataclass CoreDataStack: NSObject {// MARK: - Properties let context: NSManagedObjectContextlet coordinator: NSPersistentStoreCoordinatorlet model: NSManagedObjectModellet store: NSPersistentStore?// MARK: - Singletonstatic func defaultStack() -> CoreDataStack {return instance}fileprivate static let instance = CoreDataStack()fileprivate override init() {// 構(gòu)建托管對(duì)象模型let bundle = Bundle.mainlet modelURL = bundle.url(forResource: "Test", withExtension: "momd")!model = NSManagedObjectModel(contentsOf: modelURL)!// 構(gòu)建持久化存儲(chǔ)助理coordinator = NSPersistentStoreCoordinator(managedObjectModel: model)// 構(gòu)建托管對(duì)象上下文，并且將助理連接到上下文context = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)context.persistentStoreCoordinator = coordinator// 構(gòu)建持久化存儲(chǔ)let manager = FileManager.defaultlet urls = manager.urls(for: .documentDirectory, in: .userDomainMask)let documentsURL = urls.first!let storeURL = documentsURL.appendingPathComponent("Test")store = (try! coordinator.addPersistentStore(ofType: NSSQLiteStoreType,configurationName: nil, at: storeURL, options: nil))}// MARK: - Function func saveContext () {if context.hasChanges {do {try context.save()} catch {print("Save failed...")}}} }

接著實(shí)現(xiàn)數(shù)據(jù)操作

//新增數(shù)據(jù) func insertStudent(sno: String, name: String, score: Int) {// 獲取上下文（也就是從”coreData基礎(chǔ)“里面的那個(gè)類里面獲取）let context = CoreDataStack.defaultStack().context// 構(gòu)建實(shí)體對(duì)象let student = NSEntityDescription.insertNewObject(forEntityName: "Student",into: context) as! Student// 設(shè)置相關(guān)屬性student.sno = snostudent.name = namestudent.score = score as NSNumber?}// 查詢數(shù)據(jù) func fetchStudents() {// 獲取上下文let context = CoreDataStack.defaultStack().context// 構(gòu)建抓取請(qǐng)求let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Student")// 指定按照學(xué)號(hào)(sno)升序排列let sort = NSSortDescriptor(key: "sno", ascending: true,selector: #selector(NSString.localizedStandardCompare(_:)))request.sortDescriptors = [sort]// 構(gòu)建查詢條件 // request.predicate = NSPredicate(format: "score > 60") // request.predicate = NSPredicate(format: "name like 'a*'")do {let students = (try context.fetch(request)) as! [Student]for student in students {print("\(student.sno!), \(student.name!), \(student.score!)")}} catch {print("Fetch failed...")}}// 統(tǒng)計(jì)信息 func countStudents() { // // 1. 統(tǒng)計(jì)分?jǐn)?shù)大于90的人數(shù) // // // 獲取上下文 // let context = CoreDataStack.defaultStack().context // // // 構(gòu)建抓取請(qǐng)求 // let request = NSFetchRequest(entityName: "Student") // request.predicate = NSPredicate(format: "score > 90") // request.resultType = .CountResultType // // do { // let entries = (try context.executeFetchRequest(request)) // let count = entries.first!.integerValue // print("Count: \(count)") // } catch { // print("Fetch failed...") // }// 2. 計(jì)算平均分?jǐn)?shù)// 獲取上下文let context = CoreDataStack.defaultStack().context// 構(gòu)建抓取請(qǐng)求let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Student")request.resultType = .dictionaryResultType // 指定返回結(jié)果為字典// 構(gòu)建表達(dá)式let description = NSExpressionDescription()description.name = "AverageScore"let args = [NSExpression(forKeyPath: "score")]description.expression = NSExpression(forFunction: "average:", arguments: args)description.expressionResultType = .floatAttributeType // 指定返回值類型// 將求平均值的表達(dá)式設(shè)置給request的屬性request.propertiesToFetch = [description]do {let entries = (try context.fetch(request))let result = entries.first! as! NSDictionarylet averageScore = result["AverageScore"]!print("Average: \(averageScore)")} catch {print("Fetch failed...")}}// 修改數(shù)據(jù) func updateStudents() {// 獲取上下文let context = CoreDataStack.defaultStack().context// 構(gòu)建抓取請(qǐng)求let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Student")request.predicate = NSPredicate(format: "name like 'a*'")do {let students = (try context.fetch(request)) as! [Student]for student in students {student.score = 100}} catch {print("Fetch failed...")}// 保存 CoreDataStack.defaultStack().saveContext()// 備注: 批量更新 & 異步操作 ??? }// 刪除數(shù)據(jù) func deleteStudents() {// 獲取上下文let context = CoreDataStack.defaultStack().context// 構(gòu)建抓取請(qǐng)求let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Student")request.predicate = NSPredicate(format: "score < 60")do {let students = (try context.fetch(request)) as! [Student]for student in students {context.delete(student)}} catch {print("Fetch failed...")}// 保存 CoreDataStack.defaultStack().saveContext()} 總結(jié)： 增： 1:獲取上下文 如：let context = CoreDataStack.defaultStack().context 2:構(gòu)建實(shí)體對(duì)象 如：let student = NSEntityDescription.insertNewObject(forEntityName: "Student", into: context) as! Student 3:設(shè)置相關(guān)屬性 如： student.sno = sno 4:保存數(shù)據(jù) 如：CoreDataStack.defaultStack().saveContext() ? 修改，刪除 1:獲取上下文 2:構(gòu)建抓取請(qǐng)求 如:let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Student") 3:給抓去請(qǐng)求設(shè)置相關(guān)屬性吧 如： //相當(dāng)于給它設(shè)置約束 request.predicate = NSPredicate(format: "name like 'a*'") // 指定返回結(jié)果為字典（修改，刪除一般不用設(shè)置這個(gè)） request.resultType = .dictionaryResultType 4:執(zhí)行抓取操作 do { let students = (try context.fetch(request)) as! [Student] for student in students { //修改如：student.score = 100 //刪除如：context.delete(student) } } catch { print("Fetch failed...") } 5:保存數(shù)據(jù) ? 查詢 1:獲取上下文 2:構(gòu)建抓取請(qǐng)求 3:指定按照學(xué)號(hào)(sno)升序排列（其實(shí)此部可以省略） let sort = NSSortDescriptor(key: "sno", ascending: true, selector: #selector(NSString.localizedStandardCompare(_:))) request.sortDescriptors = [sort] 4:執(zhí)行抓取語句 do { let students = (try context.fetch(request)) as! [Student] for student in students { print("\(student.sno!), \(student.name!), \(student.score!)") } } catch { print("Fetch failed...") } 5:釋放資源 ? 統(tǒng)計(jì) 1:獲取上下文 2:構(gòu)建抓取請(qǐng)求 3:指定按照學(xué)號(hào)(sno)升序排列（其實(shí)此部可以省略） let sort = NSSortDescriptor(key: "sno", ascending: true, selector: #selector(NSString.localizedStandardCompare(_:))) request.sortDescriptors = [sort] 4: 構(gòu)建表達(dá)式(average是聚合函數(shù)，當(dāng)然還有其他的) 如：let description = NSExpressionDescription() description.name = "AverageScore" let args = [NSExpression(forKeyPath: "score")] description.expression = NSExpression(forFunction: "average:", arguments: args) description.expressionResultType = .floatAttributeType // 指定返回值類型 5:將求平均值的表達(dá)式設(shè)置給request的屬性 如request.propertiesToFetch = [description] 4:執(zhí)行抓取語句 do { let entries = (try context.fetch(request)) let result = entries.first! as! NSDictionary let averageScore = result["AverageScore"]! print("Average: \(averageScore)") } catch { print("Fetch failed...") } 5:釋放資源 ? 當(dāng)然，這個(gè)只是一個(gè)例子而已，不是所有的統(tǒng)計(jì)例子都要那么復(fù)雜的 如下面這個(gè)例子 // 1. 統(tǒng)計(jì)分?jǐn)?shù)大于90的人數(shù) // // // 獲取上下文 // let context = CoreDataStack.defaultStack().context // // // 構(gòu)建抓取請(qǐng)求 // let request = NSFetchRequest(entityName: "Student") // request.predicate = NSPredicate(format: "score > 90") // request.resultType = .CountResultType // // do { // let entries = (try context.executeFetchRequest(request)) // let count = entries.first!.integerValue // print("Count: \(count)") // } catch { // print("Fetch failed...") // }

轉(zhuǎn)載于:https://www.cnblogs.com/LarryBlogger/p/6186655.html

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