如何取回 iPhone 相机胶卷上保存的照片？

Question

我是 iOS 开发的新手，我正在尝试创建一个允许用户使用相机拍照的视图。

我想要发生的是当用户拍摄照片时，它将照片保存到他们的相机胶卷中。我相信可以通过以下语句简单地完成：

//Let's say the image you want to save is in a UIImage called "imageToBeSaved"
UIImageWriteToSavedPhotosAlbum(imageToBeSaved, nil, nil, nil);

但是，我的问题是，如果用户离开视图然后返回视图，我仍然希望该图片存在。那么如何取回我之前拍摄/保存的同一张照片，以便在他们重新打开视图时重新加载它？

任何帮助都会很棒！谢谢。

Answer 1

此代码 sn-p 将从相机胶卷中获取最新图像：reference link

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");
}];

Answer 2

void UIImageWriteToFile(UIImage *image, NSString *fileName)
{
    NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDirectoryPath = dirPaths[0];
    NSString *filePath = [documentDirectoryPath stringByAppendingPathComponent:fileName];

    NSData *imageData = UIImagePNGRepresentation(image);
    [imageData writeToFile:filePath atomically:YES];
}

void UIImageReadFromFile(UIImage **image, NSString *fileName)
{
    NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDirectoryPath = dirPaths[0];
    NSString *filePath = [documentDirectoryPath stringByAppendingPathComponent:fileName];

    image = [UIImage imageWithContentsOfFile:filePath];
}

图像将被保存到您的应用程序包的 Documents 目录并从中读取指定名称。

使用示例：

UIImageWriteToFile(image, @"somephoto.png");

UIImage *fetchedImage;
UIImageReadFromFile(&fetchedImage, @"somephoto.png");