iOS：从相机胶卷中获取最后一张图像

Question

我想要最后一张保存在相机胶卷中的图像。 我已经搜索了它，但是获得了iOS 9中不推荐使用的ALAssetsLibrary的结果，所以请为此提供解决方案，因为我没有得到适当的解决方案。

我想要目标C中的解决方案。

Answer 1

请检查此代码...可能会对您有所帮助。

PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:YES]];
PHFetchResult *fetchResult = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:fetchOptions];
PHAsset *lastAsset = [fetchResult lastObject];
[[PHImageManager defaultManager] requestImageForAsset:lastAsset
                                          targetSize:self.photoLibraryButton.bounds.size
                                         contentMode:PHImageContentModeAspectFill
                                             options:PHImageRequestOptionsVersionCurrent
                                       resultHandler:^(UIImage *result, NSDictionary *info) {

                                           dispatch_async(dispatch_get_main_queue(), ^{

                                               [[self photoLibraryButton] setImage:result forState:UIControlStateNormal];

                                           });
                                       }];

Answer 2

在iOS 8中，Apple添加了“照片”库，该库使查询更加轻松。

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)
                })
            }
        }
    }
}