iOS開發之獲取系統相冊中的圖片與視頻(內帶url轉換)

@話不多說,直接上代碼

#import <AssetsLibrary/AssetsLibrary.h>  // 必須導入

// 照片原圖路徑
#define KOriginalPhotoImagePath   \
[[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"OriginalPhotoImages"]

// 視頻URL路徑
#define KVideoUrlPath   \
[[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"VideoURL"]

// caches路徑
#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];

    // 測試BarItem
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"測試" style:UIBarButtonItemStylePlain target:self action:@selector(testRun)];

    // 測試手勢
    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(didClickPanGestureRecognizer:)];
    [self.navigationController.view addGestureRecognizer:panRecognizer];

    // 圖片或者視頻的縮略圖顯示
    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的更新記得放在主線程,要不然等子線程排隊過來都不知道什麼年代了,會很慢的
                                dispatch_async(dispatch_get_main_queue(), ^{
                                    self.litimgView.image = image;
                                });
                            }
                            // 視頻
                            else if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypeVideo] ){

                                // 和圖片方法類似
                            }
                        }
                    }];
                }];

            }
        };

        ALAssetsLibraryAccessFailureBlock failureBlock = ^(NSError *error)
        {

            NSString *errorMessage = nil;

            switch ([error code]) {
                case ALAssetsLibraryAccessUserDeniedError:
                case ALAssetsLibraryAccessGloballyDeniedError:
                    errorMessage = @"用戶拒絕訪問相冊,請在<隱私>中開啓";
                    break;

                default:
                    errorMessage = @"Reason unknown.";
                    break;
            }

            dispatch_async(dispatch_get_main_queue(), ^{
                UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"錯誤,無法訪問!"
                                                                   message:errorMessage
                                                                  delegate:self
                                                         cancelButtonTitle:@"確定"
                                                         otherButtonTitles:nil, nil nil];
                [alertView show];
            });
        };


        ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc]  init];
        [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll
                                     usingBlock:listGroupBlock failureBlock:failureBlock];
    });
}

      @但是:

      按照上面方法直接取出來的路徑是無法傳輸的,必須自己轉化成NSData對象重新寫入沙盒路徑

// 將原始圖片的URL轉化爲NSData數據,寫入沙盒
- (void)imageWithUrl:(NSURL *)url withFileName:(NSString *)fileName
{
    // 進這個方法的時候也應該加判斷,如果已經轉化了的就不要調用這個方法了
    // 如何判斷已經轉化了,通過是否存在文件路徑
    ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init];
    // 創建存放原始圖的文件夾--->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];
        }
    });
}

// 將原始視頻的URL轉化爲NSData數據,寫入沙盒
- (void)videoWithUrl:(NSURL *)url withFileName:(NSString *)fileName
{
    // 解析一下,爲什麼視頻不像圖片一樣一次性開闢本身大小的內存寫入?
    // 想想,如果1個視頻有1G多,難道直接開闢1G多的空間大小來寫?
    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;
                    // 初始化一個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);//沒到結尾，沒出錯，ok繼續
                    }
                    // 釋放緩衝區，關閉文件
                    free(buffer);
                    buffer = NULL;
                    fclose(file);
                    file = NULL;
                }
            } failureBlock:nil];
        }
    });
}

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