Swift - 使用ALAssetsLibrary获取相簿里所有图片，视频（附样例）

1，ALAssetsLibrary介绍
（1）通过创建ALAssetsLibrary的实例可以访问系统Photos里的图片与视频。这里图片不仅包括相机拍摄的照片，还包括从iTunes导入的和从其他设备里面导入的图片。
（2）从ALAssetsLibrary实例中获取得到的对象的生命周期和ALAssetsLibrary这个实例的生命周期一致。

（3）通过enumerateGroupsWithTypes方法可以遍历所有的照片分组，再用分组的enumerateAssetsUsingBlock方法可以遍历该分组下所有的照片。

（4）通过valueForProperty获取到图片的信息，包括类型， Location , 时长，方向，日期，格式 ， URL地址

2，下面做一个查看相册图片的APP

（1）程序启动后会加载相机胶卷里所有的照片，并以缩略图的形式展示出来

（2）点击缩略图，可以查看照片的原图以及图片的相关信息

3，效果图如下：

    

4，详细代码

--- 首页 ViewController.swift ---

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import UIKit import AssetsLibrary   class ViewController: UICollectionViewController {     //资源库管理类     var assetsLibrary =  ALAssetsLibrary()     //保存照片集合     var assets = [ALAsset]()       override func viewDidLoad() {         super.viewDidLoad()                   var countOne = 0         //ALAssetsGroupSavedPhotos表示只读取相机胶卷（ALAssetsGroupAll则读取全部相簿）         assetsLibrary.enumerateGroupsWithTypes(ALAssetsGroupSavedPhotos, usingBlock: {             (group: ALAssetsGroup!, stop) in             println("is goin")             if group != nil             {                 var assetBlock : ALAssetsGroupEnumerationResultsBlock = {                     (result: ALAsset!, index: Int, stop) in                     if result != nil                     {                         self.assets.append(result)                         countOne++                     }                 }                 group.enumerateAssetsUsingBlock(assetBlock)                 println("assets:\(countOne)")                 //collectionView网格重载数据                 self.collectionView?.reloadData()             }             }, failureBlock: { (fail) in                 println(fail)         })     }              // CollectionView行数     override func collectionView(collectionView: UICollectionView,         numberOfItemsInSection section: Int) -> Int {             return assets.count;     }           // 获取单元格     override func collectionView(collectionView: UICollectionView,         cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {             // storyboard里设计的单元格             let identify:String = "DesignViewCell"             // 获取设计的单元格，不需要再动态添加界面元素             let cell = self.collectionView?.dequeueReusableCellWithReuseIdentifier(                 identify, forIndexPath: indexPath) as! UICollectionViewCell                           //取缩略图             var myAsset = assets[indexPath.item]             var image = UIImage(CGImage:myAsset.thumbnail().takeUnretainedValue())             // 从界面查找到控件元素并设置属性             (cell.contentView.viewWithTag(1) as! UIImageView).image = image             return cell     }           // 单元格点击响应     override func collectionView(collectionView: UICollectionView,         didSelectItemAtIndexPath indexPath: NSIndexPath) {         var myAsset = assets[indexPath.item]                   //这里不使用segue跳转（建议用segue跳转）         var detailViewController = UIStoryboard(name: "Main", bundle: nil)             .instantiateViewControllerWithIdentifier("detail") as! ImageDetailViewController         detailViewController.myAsset = self.assets[indexPath.row]         // navigationController跳转到detailViewController         self.navigationController!.pushViewController(detailViewController, animated:true)     }           override func didReceiveMemoryWarning() {         super.didReceiveMemoryWarning()         // Dispose of any resources that can be recreated.     } }

--- 详情页 ImageDetailViewController.swift ---

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import UIKit import AssetsLibrary   class ImageDetailViewController: UIViewController {     //选中的图片资源     var myAsset:ALAsset!     //用于显示图片信息     @IBOutlet weak var textView: UITextView!     //用于显示原图     @IBOutlet weak var imageView: UIImageView!           override func viewDidLoad() {         super.viewDidLoad()                   //获取文件名         var representation =  myAsset.defaultRepresentation()         self.title = representation.filename()                   //获取图片信息         textView.text = "日期：\(myAsset.valueForProperty(ALAssetPropertyDate))\n"             + "类型：\(myAsset.valueForProperty(ALAssetPropertyType))\n"             + "位置：\(myAsset.valueForProperty(ALAssetPropertyLocation))\n"             + "时长：\(myAsset.valueForProperty(ALAssetPropertyDuration))\n"             + "方向：\(myAsset.valueForProperty(ALAssetPropertyOrientation))"                   //获取原图         var imageBuffer = UnsafeMutablePointer<UInt8>.alloc(Int(representation.size()))         var bufferSize = representation.getBytes(imageBuffer, fromOffset: Int64(0),             length: Int(representation.size()), error: nil)         var data =  NSData(bytesNoCopy:imageBuffer ,length:bufferSize, freeWhenDone:true)         imageView.image = UIImage(data: data)     }       override func didReceiveMemoryWarning() {         super.didReceiveMemoryWarning()         // Dispose of any resources that can be recreated.     } }

5，源码下载：PhotoViewer.zip