iOS - 获取手机中所有图片

  1 #import <AssetsLibrary/AssetsLibrary.h>

   /**
  6  *  ALAssetsLibrary.h 代表资源库(所有的视频,照片)
  7     ALAssetsGroup.h   代表资源库中的相册
  8     ALAsset.h         代表相册中一个视频或者一张照片
  9     ALAssetRepresentation.h 代表一个资源的描述,可以获取到原始图片
 10  */

  @interface ViewController ()

  @property (weak, nonatomic) IBOutlet UICollectionView *collectionView;

  @property (nonatomic,strong)NSMutableArray *array;
  @end

  @implementation ViewController{

      ALAssetsLibrary *library;

  }

  - (void)viewDidLoad {
      [super viewDidLoad];

      //创建可变数组,存储资源文件
      _array = [NSMutableArray array];

      //创建资源库,用于访问相册资源
      library = [[ALAssetsLibrary alloc] init];

      //遍历资源库中所有的相册,有多少个相册,usingBlock会调用多少次
      [library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {

          //如果存在相册,再遍历
          if (group) {

              //遍历相册中所有的资源(照片,视频)
             [group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {

                 /*
 44                 资源的索引
 45                if (index == 2) {
 46
 47                 //停止遍历
 48                    *stop = YES;
 49                }
 50                 */

                 if (result) {
                     //将资源存储到数组中
                     [_array addObject:result];
                 }

             }];
          }

          //刷新_collectionView reloadData;
           [_collectionView reloadData];

      } failureBlock:^(NSError *error) {

          NSLog(@"访问失败");
      }];

  }

  #pragma mark -UICollectionViewDelegate

  //行的个数
  - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {

      return _array.count;

  }

  //创建UICollectionViewCell
  - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {

      //如果单元格是在故事版中画出来的,不需要注册,需要在单元格中指定标识符
      UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];

      //取得图片视图
      UIImageView *imgView = (UIImageView *)[cell.contentView viewWithTag:];

      //取出对应的资源数据
       ALAsset *result =_array[indexPath.row];

      //获取到缩略图
      CGImageRef cimg = [result thumbnail];

      //转换为UIImage
      UIImage *img = [UIImage imageWithCGImage:cimg];

      //显示图片
      imgView.image = img;

     /**
102      *  获取到原始图片
103      ALAssetRepresentation *presentation = [result defaultRepresentation];
104
105     CGImageRef resolutionImg = [presentation fullResolutionImage];
106      */

     return cell;

 }

 //单元格大小
 - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{

     return CGSizeMake(, );