如何从iOS上的相机​​胶卷检索最近的照片？

我很难找出如何以编程方式检索相机胶卷中最近的照片，而无需用户干预。 要清楚，我不想使用图像select器，我希望应用程序在应用程序打开时自动获取最新的照片。

我知道这是可能的，因为我见过类似的应用程序做，但我似乎无法find任何信息。

Answer 1

一种方法是使用AssetsLibrary，并使用n – 1作为枚举的索引。

ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init]; [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) { if (nil != group) { // be sure to filter the group so you only get photos [group setAssetsFilter:[ALAssetsFilter allPhotos]]; if (group.numberOfAssets > 0) { [group enumerateAssetsAtIndexes:[NSIndexSet indexSetWithIndex:group.numberOfAssets - 1] options:0 usingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) { if (nil != result) { ALAssetRepresentation *repr = [result defaultRepresentation]; // this is the most recent saved photo UIImage *img = [UIImage imageWithCGImage:[repr fullResolutionImage]]; // we only need the first (most recent) photo -- stop the enumeration *stop = YES; } }]; } } *stop = NO; } failureBlock:^(NSError *error) { NSLog(@"error: %@", error); }]; 

Answer 2

而不是搞乱索引，你可以通过列表反向枚举。 如果您想要最近的图像，或者如果您想在最近的图像的UICollectionView中列出图像，此模式效果很好。

返回最新图像的示例：

 [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop) { if (asset) { ALAssetRepresentation *repr = [asset defaultRepresentation]; UIImage *img = [UIImage imageWithCGImage:[repr fullResolutionImage]]; *stop = YES; } }]; 

Answer 3

在iOS 8中，苹果添加了照片库 ，这使查询更容易。 在iOS 9中， 不推荐使用 ALAssetLibrary 。

这里有一些Swift代码来获取该框架最近拍摄的照片。

 import UIKit import Photos struct LastPhotoRetriever { func queryLastPhoto(resizeTo size: CGSize?, queryCallback: (UIImage? -> Void)) { let fetchOptions = PHFetchOptions() fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)] // fetchOptions.fetchLimit = 1 // This is available in iOS 9. if let fetchResult = PHAsset.fetchAssetsWithMediaType(PHAssetMediaType.Image, options: fetchOptions) { if let asset = fetchResult.firstObject as? PHAsset { let manager = PHImageManager.defaultManager() // If you already know how you want to resize, // great, otherwise, use full-size. let targetSize = size == nil ? CGSize(width: asset.pixelWidth, height: asset.pixelHeight) : size! // I arbitrarily chose AspectFit here. AspectFill is // also available. manager.requestImageForAsset(asset, targetSize: targetSize, contentMode: .AspectFit, options: nil, resultHandler: { image, info in queryCallback(image) }) } } } } 

Answer 4

要添加到艺术Gillespie的答案，使用fullResolutionImage使用原始图像 – 取决于设备的方向时拍摄照片 – 可能会让你倒过来，或-90°图像。

要获得修改，但优化的图像，请使用fullScreenImage代替….

  UIImage *img = [UIImage imageWithCGImage:[repr fullScreenImage]]; 

Answer 5

Swift 3.0：

1）在你的类声明之前在头文件中导入Photos框架。

 import Photos 

2）添加下面的方法，它返回最后一个图像。

 func queryLastPhoto(resizeTo size: CGSize?, queryCallback: @escaping ((UIImage?) -> Void)) { let fetchOptions = PHFetchOptions() fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)] let requestOptions = PHImageRequestOptions() requestOptions.isSynchronous = true let fetchResult = PHAsset.fetchAssets(with: PHAssetMediaType.image, options: fetchOptions) if let asset = fetchResult.firstObject { let manager = PHImageManager.default() let targetSize = size == nil ? CGSize(width: asset.pixelWidth, height: asset.pixelHeight) : size! manager.requestImage(for: asset, targetSize: targetSize, contentMode: .aspectFit, options: requestOptions, resultHandler: { image, info in queryCallback(image) }) } } 

3）然后调用这个方法在你的应用程序的某个地方（也许是一个button操作）：

 @IBAction func pressedLastPictureAttachmentButton(_ sender: Any) { queryLastPhoto(resizeTo: nil){ image in print(image) } } 

Answer 6

回答这个问题（在Swift中 ）：

  func pickingTheLastImageFromThePhotoLibrary() { let assetsLibrary: ALAssetsLibrary = ALAssetsLibrary() assetsLibrary.enumerateGroupsWithTypes(ALAssetsGroupSavedPhotos, usingBlock: { (let group: ALAssetsGroup!, var stop: UnsafeMutablePointer<ObjCBool>) -> Void in if (group != nil) { // Be sure to filter the group so you only get photos group.setAssetsFilter(ALAssetsFilter.allPhotos()) group.enumerateAssetsWithOptions(NSEnumerationOptions.Reverse, usingBlock: { (let asset: ALAsset!, let index: Int, var stop: UnsafeMutablePointer<ObjCBool>) -> Void in if(asset != nil) { /* Returns a CGImage representation of the asset. Using the fullResolutionImage uses the original image which — depending on the device's orientation when taking the photo — could leave you with an upside down, or -90° image. To get the modified, but optimised image for this, use fullScreenImage instead. */ // let myCGImage: CGImage! = asset.defaultRepresentation().fullResolutionImage().takeUnretainedValue() /* Returns a CGImage of the representation that is appropriate for displaying full screen. */ // let myCGImage: CGImage! = asset.defaultRepresentation().fullScreenImage().takeUnretainedValue() /* Returns a thumbnail representation of the asset. */ let myCGImage: CGImage! = asset.thumbnail().takeUnretainedValue() // Here we set the image included in the UIImageView self.myUIImageView.image = UIImage(CGImage: myCGImage) stop.memory = ObjCBool(true) } }) } stop.memory = ObjCBool(false) }) { (let error: NSError!) -> Void in println("A problem occurred: \(error.localizedDescription)") } } 

Answer 7

使用照片库（Objective-C）

  PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init]; fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]]; PHFetchResult *assetsFetchResult = [PHAsset fetchAssetsInAssetCollection:assetCollection options:fetchOptions]; if (assetsFetchResult.count>0) { PHAsset *asset = [assetsFetchResult objectAtIndex:0]; CGFloat scale = [UIScreen mainScreen].scale; CGFloat dimension = 55.0f; // set your required size CGSize size = CGSizeMake(dimension*scale, dimension*scale); [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:size contentMode:PHImageContentModeAspectFit options:nil resultHandler:^(UIImage *result, NSDictionary *info) { // do your thing with the image } ]; }