swift语言IOS8开发战记22 Core Data3

标签：coredata   data model   swift   ios   

    上一话我们定义了与coredata有关的变量和方法，做足了准备工作，这一话我们来试试能不能成功。首先打开上一话中生成的Info类，在其中引用头文件的地方添加一个@objc（Info），不然后面会报错，我也不知道为什么。

然后在viewController中添加代码如下代码来实现：

import UIKit
import CoreData

class ViewController: UIViewController {
    var tempInfo: Info!
    override func viewDidLoad() {
        super.viewDidLoad()
        if let managementContext = (UIApplication.sharedApplication().delegate as
            AppDelegate).managedObjectContext{
        tempInfo = NSEntityDescription.insertNewObjectForEntityForName("Info", inManagedObjectContext: managementContext) as Info
                //相当于取到了Info，可以进行赋值操作
                tempInfo.name = "cg"
                tempInfo.location = "xidian"
                //记得save
                var e: NSError?
                
                if managementContext.save(&e) != true {
                println("insert error \(e!.localizedDescription)")
                }
                
                if let managementContext = (UIApplication.sharedApplication().delegate as AppDelegate).managedObjectContext{
                var fetchRequest = NSFetchRequest(entityName: "Info")
                    var result = managementContext.executeFetchRequest(fetchRequest, error: &e) as [Info]
                    
                    if e != nil {
                        println("fetch result error: \(e!.localizedDescription)")
                    } else {
                        for item: AnyObject in result {
                            let temp = item as Info
                            println("name: \(temp.name), localtion: \(temp.location)")
                        }
                    }
                }
        }

    }

}

    有了插入和查询，下面实现更新操作，在上面的代码中增加如下代码：

                if let managementContext = (UIApplication.sharedApplication().delegate as AppDelegate).managedObjectContext {
                var fetchRequest = NSFetchRequest(entityName: "Info")
                    fetchRequest.predicate = NSPredicate(format: "name = 'cg'", argumentArray: nil)
                    var result = managementContext.executeFetchRequest(fetchRequest, error: &e) as [Info]
                    
                    if e != nil {
                        println("fetch result error: \(e!.localizedDescription)")
                    } else {
                        for item: AnyObject in result {
                            let temp = item as Info
                            temp.name = "cggggg"
                            println("name: \(temp.name), localtion: \(temp.location)")
                        }
                        managementContext.save(&e)
                    }
                
                }

   现在来实现删除的操作，与update的操作类似，在update代码的基础上把修改名字的代码改成：

managementContext.deleteObject(temp)

swift语言IOS8开发战记22 Core Data3

标签：coredata   data model   swift   ios   

原文地址：http://blog.csdn.net/cg1991130/article/details/43895859