如何将图像文件从iOS照片库（ALAssetsLibrary）复制到应用程序的本地目录？

我可以通过ALAssetsLibrary从照片库中获取图像：

void (^assetEnumerator)(ALAsset *, NSUInteger, BOOL *) = ^(ALAsset *result, NSUInteger index, BOOL *stop){ if([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) { // Copy the photo image to the `/Documents` directory of this App here } }; void (^assetGroupEnumerator )(ALAssetsGroup*, BOOL*) = ^(ALAssetsGroup *group, BOOL *stop){ if (group != nil) { [group enumerateAssetsUsingBlock:assetEnumerator]; } }; // fetch ALAssetsLibrary *library = [ALAssetsLibrary new]; [library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:assetGroupEnumerator failureBlock:^(NSError *error) { NSLog(@"failed"); }]; 

我想将特定图像复制到本地目录（ App_home/Documents ），但我不知道如何通过处理ALAsset对象来完成这项工作。

Answer 1

尝试使用以下代码

 ALAssetsLibrary *assetLibrary=[[ALAssetsLibrary alloc] init]; [assetLibrary assetForURL:YourURL resultBlock:^(ALAsset *asset) { ALAssetRepresentation *rep = [asset defaultRepresentation]; Byte *buffer = (Byte*)malloc(rep.size); NSUInteger buffered = [rep getBytes:buffer fromOffset:0 length:rep.size error:nil]; NSData *data = [NSData dataWithBytesNoCopy:buffer length:buffered freeWhenDone:YES];//this is NSData may be what you want [data writeToFile:photoFile atomically:YES];//you can save image later } failureBlock:^(NSError *err) { NSLog(@"Error: %@",[err localizedDescription]); } ]; 

用于获取Image In文档目录

 NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *newPath = [documentsDirectory stringByAppendingPathComponent:@"Your_Image_Name"]; UIImage *myImg = [UIImage imageWithContentsOfFile:newPath] 

Answer 2

它可能对你有所帮助。 在这里，outputFileURL的类型为NSURL

  NSData *videoData = [NSData dataWithContentsOfURL:outputFileURL]; [data writeToFile:destinationPath atomically:YES];//you can save image later 

Answer 3

您可以使用以下实现获取照片原始二进制文件并保存到目标文件。

 + (NSData *)photoAssetRawData:(ALAsset *)photoAsset error:(NSError **)error { ALAssetRepresentation *rep = photoAsset.defaultRepresentation; NSMutableData *data = [NSMutableData new]; long long offset = 0; uint8_t dataBuffer[PHOTO_READ_CHUNK_SIZE]; NSError *internalError; do { NSUInteger readByteLength = [rep getBytes:dataBuffer fromOffset:offset length:sizeof(dataBuffer) error:&internalError]; if(internalError != nil) { if(error != NULL) { *error = internalError; } return nil; } offset += readByteLength; [data appendBytes:(void*)dataBuffer length:readByteLength]; } while (offset < rep.size); return data; } 

有一点必须要注意，这个原始数据没有应用任何filteriOS默认库应用程序添加，如果你想要应用这些filter，你应该从[ALAssetRepresentation元数据]获取这些XMP喜欢filter并使用[CIFilter filterArrayFromSerializedXMP：inputImageExtent：error创建filter：]，然后将它们应用于全分辨率图像，最后将此处理后的图像保存为JPEG或PNG文件。

下面显示了如何应用这些filter。

 + (CGImageRef)applyXMPFilter:(ALAsset *)asset{ ALAssetRepresentation *rep = [asset defaultRepresentation]; CGImageRef imageRef = [rep fullResolutionImage]; NSString *adjustmentXMP; NSData *adjustmentXMPData; NSError *__autoreleasing error = nil; NSArray *filters=nil; CGRect extend = CGRectZero; //add filter to image ALAssetRepresentation *representation = asset.defaultRepresentation; adjustmentXMP = [representation.metadata objectForKey:@"AdjustmentXMP"]; adjustmentXMPData = [adjustmentXMP dataUsingEncoding:NSUTF8StringEncoding]; extend.size = representation.dimensions; filters = [CIFilter filterArrayFromSerializedXMP:adjustmentXMPData inputImageExtent:extend error:&error]; if(filters) { CIImage *image = [CIImage imageWithCGImage:imageRef]; CIContext *context = [CIContext contextWithOptions:nil]; for (CIFilter *filter in filters) { [filter setValue:image forKey:kCIInputImageKey]; image = [filter outputImage]; } imageRef = [context createCGImage:image fromRect:image.extent]; } return imageRef; }