iOS实现微信/QQ显示最近拍摄图片的功能实例代码

importUIKit

importPhotos//使用图库功能时必须引用这个包

//显示最近拍摄的照片为缩略图

classViewController: UIViewController, PHPhotoLibraryChangeObserver {

 var assetsFetchResults:PHFetchResult!

 var imageManager: PHCachingImageManager!//带缓存的图片管理对象

 var imageView: UIImageView!//用于显示缩略图

 var assetGridThumbnailSize: CGSize!//缩略图大小

 override func viewDidLoad() {

  super.viewDidLoad()

  // Do any additional setup after loading the view, typically from a nib.

  imageView = UIImageView()

  imageView.frame = CGRect(x:50, y:50, width:100, height:100)

  imageView.contentMode = .scaleAspectFit

  imageView.clipsToBounds =true

  self.view.addSubview(imageView)

  self.imageManager = PHCachingImageManager()//初始化和充值缓存

  let scale = UIScreen.main.scale//像素比

  assetGridThumbnailSize = CGSize(width: imageView.frame.width*scale,

          height: imageView.frame.height*scale)

  //申请权限

  PHPhotoLibrary.requestAuthorization({ (status) in

   ifstatus != .authorized {

    return

   }

   //获取所有图片资源(按照创建时间排序)

   let allPhotoOptions = PHFetchOptions()

   allPhotoOptions.sortDescriptors = [NSSortDescriptor(key:"creationDate",

                ascending:false)]//排序方式

   allPhotoOptions.predicate = NSPredicate(format:"mediaType = %d",

             PHAssetMediaType.image.rawValue)//类型

   self.assetsFetchResults = PHAsset.fetchAssets(with: .image,

               options: allPhotoOptions)//查询照片类型

   var i =0

   whilei

    let asset = self.assetsFetchResults[i]

    print(" 创建时间：\(asset.creationDate?.description)")//打印所有图片的创建时间

    i +=1

   }

   if(self.assetsFetchResults.count >0) {

    //显示最近一张拍摄的图片（也可以根据拍摄时间远近决定是否要显示）

    self.imageManager.requestImage(for: self.assetsFetchResults[0], //最近一张图片

            targetSize: self.assetGridThumbnailSize,

            contentMode: .aspectFill,

            options: nil, resultHandler: { (image, info) in

            self.imageView.image = image//取出图像并显示出来

    })

   }

   print("图片数量：\(self.assetsFetchResults?.count)")

   //注册监听资源变化

   PHPhotoLibrary.shared().register(self)//删除是unregisterChangeObserver

  })

 }

 override func didReceiveMemoryWarning() {

  super.didReceiveMemoryWarning()

  // Dispose of any resources that can be recreated.

 }

 func photoLibraryDidChange(_ changeInstance: PHChange) {

  guard let changes = changeInstance.changeDetails(for: self.assetsFetchResults as! PHFetchResult)else{

   return

  }

  //异步执行，避免阻塞图片变化事件队列

  DispatchQueue.main.async {

   iflet result = changes.fetchResultAfterChanges as? PHFetchResult{

    self.assetsFetchResults = result//差异结果

   }

   //判断是否有新增图片或删除图片的情况

   if!changes.hasIncrementalChanges || changes.hasMoves {

    return

   }else{

    print("图片数据有变化")

    iflet indexs = changes.changedIndexes, indexs.count>0{//不显示0的情况

     print("有\(indexs.count)张图片发生变化")

    }

    iflet removes = changes.removedIndexes, removes.count>0{

     print("删除了\(removes.count)张图片")

    }

    iflet inserts = changes.insertedIndexes, inserts.count>0{

     //有新增图片

     print("新增了\(inserts.count)张图片")

     let picture = self.assetsFetchResults[inserts.first!]

     self.imageManager.requestImage(for: picture,

             targetSize: self.assetGridThumbnailSize,

             contentMode: .aspectFill,

             options: nil, resultHandler: { (image, option) in

             self.imageView.image = image//取出图像并显示出来

     })

    }

   }

  }

 }

}