ios - 从 Photos.app 获取最后一张图片？

Question

我看到其他应用程序也这样做，您可以从照片应用程序导入最后一张照片以便快速使用，但据我所知，我只知道如何获取 A 图像而不是最后一张照片(最近一张)。谁能告诉我如何获得最后一张图片？

Answer 1

此代码段将从相机胶卷中获取最新图像(iOS 7 及以下版本):

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];

// Enumerate just the photos and videos group by using ALAssetsGroupSavedPhotos.
[library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {

    // Within the group enumeration block, filter to enumerate just photos.
    [group setAssetsFilter:[ALAssetsFilter allPhotos]];

    // Chooses the photo at the last index
    [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *alAsset, NSUInteger index, BOOL *innerStop) {

        // The end of the enumeration is signaled by asset == nil.
        if (alAsset) {
            ALAssetRepresentation *representation = [alAsset defaultRepresentation];
            UIImage *latestPhoto = [UIImage imageWithCGImage:[representation fullScreenImage]];

            // Stop the enumerations
            *stop = YES; *innerStop = YES;

            // Do something interesting with the AV asset.
            [self sendTweet:latestPhoto];
        }
    }];
} failureBlock: ^(NSError *error) {
    // Typically you should handle an error more gracefully than this.
    NSLog(@"No groups");
}];

iOS 8 及更高版本:

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];

                                           });
                                       }];