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];     }   }); }