iOS开发之获取系统相册中的图片与视频教程(内带url转换)

#import <AssetsLibrary/AssetsLibrary.h> // 必须导入 
 
// 照片原图路径 
#define KOriginalPhotoImagePath  \ 
[[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"OriginalPhotoImages"] 
 
// 视频URL路径 
#define KVideoUrlPath  \ 
[[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"VideoURL"] 
 
// caches路径 
#define KCachesPath  \ 
[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0] 
 
// MainViewController 
@interface MTHMainViewController () 
 
@property (nonatomic,strong) MTHNextViewController *nextVC; 
@property (nonatomic,strong) NSMutableArray    *groupArrays; 
@property (nonatomic,strong) UIImageView      *litimgView; 
 
@end 
 
@implementation MTHMainViewController 
 
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
{ 
  self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
  if (self) { 
    // Custom initialization 
  } 
  return self; 
} 
 
- (void)viewDidLoad 
{ 
  [super viewDidLoad]; 
  // Do any additional setup after loading the view. 
  self.navigationItem.title = @"Demo"; 
  self.view.backgroundColor = [UIColor clearColor]; 
   
  // 初始化 
  self.groupArrays = [NSMutableArray array]; 
   
  // 测试BarItem 
  self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"测试" style:UIBarButtonItemStylePlain target:self action:@selector(testRun)]; 
   
  // 测试手势 
  UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(didClickPanGestureRecognizer:)]; 
  [self.navigationController.view addGestureRecognizer:panRecognizer]; 
   
  // 图片或者视频的缩略图显示 
  self.litimgView = [[UIImageView alloc] initWithFrame:CGRectMake(100, 200, 120, 120)]; 
  [self.view addSubview:_litimgView]; 
} 
 
 
- (void)testRun 
{ 
  __weak MTHMainViewController *weakSelf = self; 
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ 
    ALAssetsLibraryGroupsEnumerationResultsBlock listGroupBlock = ^(ALAssetsGroup *group, BOOLBOOL *stop) { 
      if (group != nil) { 
        [weakSelf.groupArrays addObject:group]; 
      } else { 
        [weakSelf.groupArrays enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOLBOOL *stop) { 
          [obj enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOLBOOL *stop) { 
            if ([result thumbnail] != nil) { 
              // 照片 
              if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]){ 
                 
                NSDate *date= [result valueForProperty:ALAssetPropertyDate]; 
                UIImage *image = [UIImage imageWithCGImage:[result thumbnail]]; 
                NSString *fileName = [[result defaultRepresentation] filename]; 
                NSURL *url = [[result defaultRepresentation] url]; 
                int64_t fileSize = [[result defaultRepresentation] size]; 
                 
                NSLog(@"date = %@",date); 
                NSLog(@"fileName = %@",fileName); 
                NSLog(@"url = %@",url); 
                NSLog(@"fileSize = %lld",fileSize); 
                 
                // UI的更新记得放在主线程,要不然等子线程排队过来都不知道什么年代了,会很慢的 
                dispatch_async(dispatch_get_main_queue(), ^{ 
                  self.litimgView.image = image; 
                }); 
              } 
              // 视频 
              else if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypeVideo] ){ 
               
                // 和图片方法类似 
              } 
            } 
          }]; 
        }]; 
 
      } 
    }; 
     
    ALAssetsLibraryAccessFailureBlock failureBlock = ^(NSError *error) 
    { 
       
      NSString *errorMessage = nil; 
       
      switch ([error code]) { 
        case ALAssetsLibraryAccessUserDeniedError: 
        case ALAssetsLibraryAccessGloballyDeniedError: 
          errorMessage = @"用户拒绝访问相册,请在<隐私>中开启"; 
          break; 
           
        default: 
          errorMessage = @"Reason unknown."; 
          break; 
      } 
       
      dispatch_async(dispatch_get_main_queue(), ^{ 
        UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"错误,无法访问!" 
                                  message:errorMessage 
                                 delegate:self 
                             cancelButtonTitle:@"确定" 
                             otherButtonTitles:nil, nil nil]; 
        [alertView show]; 
      }); 
    }; 
     
     
    ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init]; 
    [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll 
                   usingBlock:listGroupBlock failureBlock:failureBlock]; 
  }); 
} 

   // 将原始图片的URL转化为NSData数据,写入沙盒 
- (void)imageWithUrl:(NSURL *)url withFileName:(NSString *)fileName 
{ 
  // 进这个方法的时候也应该加判断,如果已经转化了的就不要调用这个方法了 
  // 如何判断已经转化了,通过是否存在文件路径 
  ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init]; 
  // 创建存放原始图的文件夹--->OriginalPhotoImages 
  NSFileManager * fileManager = [NSFileManager defaultManager]; 
  if (![fileManager fileExistsAtPath:KOriginalPhotoImagePath]) { 
    [fileManager createDirectoryAtPath:KOriginalPhotoImagePath withIntermediateDirectories:YES attributes:nil error:nil]; 
  } 
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ 
    if (url) { 
      // 主要方法 
      [assetLibrary assetForURL:url resultBlock:^(ALAsset *asset) { 
        ALAssetRepresentation *rep = [asset defaultRepresentation]; 
        Byte *buffer = (Byte*)malloc((unsigned long)rep.size); 
        NSUInteger buffered = [rep getBytes:buffer fromOffset:0.0 length:((unsigned long)rep.size) error:nil]; 
        NSData *data = [NSData dataWithBytesNoCopy:buffer length:buffered freeWhenDone:YES]; 
        NSString * imagePath = [KOriginalPhotoImagePath stringByAppendingPathComponent:fileName]; 
        [data writeToFile:imagePath atomically:YES]; 
      } failureBlock:nil]; 
    } 
  }); 
} 
 
// 将原始视频的URL转化为NSData数据,写入沙盒 
- (void)videoWithUrl:(NSURL *)url withFileName:(NSString *)fileName 
{ 
  // 解析一下,为什么视频不像图片一样一次性开辟本身大小的内存写入? 
  // 想想,如果1个视频有1G多,难道直接开辟1G多的空间大小来写? 
  ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init]; 
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ 
    if (url) { 
      [assetLibrary assetForURL:url resultBlock:^(ALAsset *asset) { 
        ALAssetRepresentation *rep = [asset defaultRepresentation]; 
        NSString * videoPath = [KCachesPath stringByAppendingPathComponent:fileName]; 
        char constconst *cvideoPath = [videoPath UTF8String]; 
        FILEFILE *file = fopen(cvideoPath, "a+"); 
        if (file) { 
          const int bufferSize = 11024 * 1024; 
          // 初始化一个1M的buffer 
          Byte *buffer = (Byte*)malloc(bufferSize); 
          NSUInteger read = 0, offset = 0, written = 0; 
          NSError* err = nil; 
          if (rep.size != 0) 
          { 
            do { 
              read = [rep getBytes:buffer fromOffset:offset length:bufferSize error:&err]; 
              written = fwrite(buffer, sizeof(char), read, file); 
              offset += read; 
            } while (read != 0 && !err);//没到结尾，没出错，ok继续 
          } 
          // 释放缓冲区，关闭文件 
          free(buffer); 
          buffer = NULL; 
          fclose(file); 
          file = NULL; 
        } 
      } failureBlock:nil]; 
    } 
  }); 
}