Swift Core Data 图片存储与读取Demo

最新推荐文章于 2020-06-29 14:41:43 发布

转载最新推荐文章于 2020-06-29 14:41:43 发布 · 139 阅读

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#swift

本文介绍如何利用Core Data框架在iOS应用中存储和读取图片数据。具体包括实体模型定义、保存图片到Core Data的方法及从Core Data中加载图片的实现。

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实体的模型定义：
这里写图片描述

这里写图片描述

实体的class定义：

@objc(ImageEntity)
class ImageEntity: NSManagedObject { @NSManaged var imageData: NSData }

存储：

@IBAction func saveImageToCoreData() {
    let delegate = UIApplication.sharedApplication().delegate as AppDelegate
    let context = delegate.managedObjectContext let imageData = UIImagePNGRepresentation(UIImage(named: "image")) let imageEntity = NSEntityDescription.entityForName("ImageEntity", inManagedObjectContext: context!) let image = ImageEntity(entity: imageEntity!, insertIntoManagedObjectContext: context!) image.imageData = imageData var error: NSError? if context!.save(&error) == false { println("failed: \(error!.localizedDescription)") } }

读取：

@IBAction func loadImageFromCoreData() {
    let delegate = UIApplication.sharedApplication().delegate as AppDelegate
    let context = delegate.managedObjectContext let request = NSFetchRequest(entityName: "ImageEntity") var error: NSError? let imageEntities = context?.executeFetchRequest(request, error: &error) let imageEntity = imageEntities?.first! as ImageEntity self.imageView.image = UIImage(data: imageEntity.imageData) }