60

我正在尝试从 PHAsset 创建一个 UIImage（如缩略图或其他东西），以便我可以将它传递给需要 UIImage 的东西。我已经尝试过调整我在 SO 上找到的解决方案（因为他们都只是直接将它传递给一个 tableview 或其他东西），但我没有成功（可能是因为我做得不对）。

func getAssetThumbnail(asset: PHAsset) -> UIImage {
    var retimage = UIImage()
    println(retimage)
    let manager = PHImageManager.defaultManager()
    manager.requestImageForAsset(asset, targetSize: CGSize(width: 100.0, height: 100.0), contentMode: .AspectFit, options: nil, resultHandler: {(result, info)->Void in
            retimage = result
    })
    println(retimage)
    return retimage
}

printlns 告诉我 manager.request 行现在没有做任何事情。如何获得它以将资产作为 UIImage 提供给我。

谢谢。

4

10 回答 10

92

这做了我需要它做的事情，以防有人也需要这个。

func getAssetThumbnail(asset: PHAsset) -> UIImage {
    let manager = PHImageManager.defaultManager()
    let option = PHImageRequestOptions()
    var thumbnail = UIImage()
    option.synchronous = true
    manager.requestImageForAsset(asset, targetSize: CGSize(width: 100.0, height: 100.0), contentMode: .AspectFit, options: option, resultHandler: {(result, info)->Void in
            thumbnail = result!
    })
    return thumbnail
}

编辑：Swift 3 更新

func getAssetThumbnail(asset: PHAsset) -> UIImage {
    let manager = PHImageManager.default()
    let option = PHImageRequestOptions()
    var thumbnail = UIImage()
    option.isSynchronous = true
    manager.requestImage(for: asset, targetSize: CGSize(width: 100, height: 100), contentMode: .aspectFit, options: option, resultHandler: {(result, info)->Void in
        thumbnail = result!
    })
    return thumbnail
}
于 2015-06-15T18:17:33.517 回答
33

试试这个对我有用，希望对你也有帮助

func getUIImage(asset: PHAsset) -> UIImage? {

    var img: UIImage?
    let manager = PHImageManager.default()
    let options = PHImageRequestOptions()
    options.version = .original
    options.isSynchronous = true
    manager.requestImageData(for: asset, options: options) { data, _, _, _ in

        if let data = data {
            img = UIImage(data: data)
        }
    }
    return img
}
于 2017-03-09T06:03:52.337 回答
23

简单的解决方案（Swift 4.2）

方法一：

extension PHAsset {

    var image : UIImage {
        var thumbnail = UIImage()
        let imageManager = PHCachingImageManager()
        imageManager.requestImage(for: self, targetSize: CGSize(width: 100, height: 100), contentMode: .aspectFit, options: nil, resultHandler: { image, _ in
            thumbnail = image!
        })
        return thumbnail
    }
}                          

let image = asset.image

如果您只需要UIImagefrom ，请使用此方法PHAsset。

或者

extension PHAsset {
    func image(targetSize: CGSize, contentMode: PHImageContentMode, options: PHImageRequestOptions?) -> UIImage {
        var thumbnail = UIImage()
        let imageManager = PHCachingImageManager()
        imageManager.requestImage(for: self, targetSize: targetSize, contentMode: contentMode, options: options, resultHandler: { image, _ in
            thumbnail = image!
        })
        return thumbnail
    }
}

let image = asset.image(targetSize: CGSize, contentMode: PHImageContentMode, options: PHImageRequestOptions?)

将此方法用于您想要的UIImage.

或者

extension PHAsset {

    func image(completionHandler: @escaping (UIImage) -> ()){
        var thumbnail = UIImage()
        let imageManager = PHCachingImageManager()
        imageManager.requestImage(for: self, targetSize: CGSize(width: 100, height: 100), contentMode: .aspectFit, options: nil, resultHandler: { img, _ in
            thumbnail = img!
        })
        completionHandler(thumbnail)
    }
}

let image = asset.image(completionHandler: {(img) in
    print("Finished")
})

完成后使用此方法进行通知。

方法二：

extension PHAsset {
    var data : (UIImage, [AnyHashable : Any]) {
        var img = UIImage(); var information = [AnyHashable : Any](); let imageManager = PHCachingImageManager()
        imageManager.requestImage(for: self, targetSize: CGSize(width: 100, height: 100), contentMode: .aspectFit, options: nil, resultHandler: { image,info in
            img = image!
            information = info!
        })
        return (img,information)
    }
} 


let image_withData : (UIImage, [AnyHashable : Any]) = asset.data

如果您想要UIImage结果信息，请使用此方法PHAsset

或者

extension PHAsset {

    func data(targetSize: CGSize, contentMode: PHImageContentMode, options: PHImageRequestOptions?) -> (UIImage, [AnyHashable : Any]) {
        var img = UIImage(); var information = [AnyHashable : Any](); let imageManager = PHCachingImageManager()
        imageManager.requestImage(for: self, targetSize: targetSize, contentMode: contentMode, options: options, resultHandler: { image,info in
            img = image!
            information = info!
        })
        return (img,information)
    }
}

let data = asset?.data(targetSize: CGSize, contentMode: PHImageContentMode, options: PHImageRequestOptions?)

将此方法用于您想要的数据。

于 2018-11-22T09:07:07.653 回答
7

我建议使用 Apple 的PHCachingImageManager（继承自 PHImageManager）：

PHCachingImageManager 对象获取或生成照片或视频资产的图像数据

此外，PHCachingImageManager 支持更好的缓存机制。

同步获取缩略图的示例：

let options = PHImageRequestOptions()
options.deliveryMode = .HighQualityFormat
options.synchronous = true // Set it to false for async callback

let imageManager = PHCachingImageManager()
imageManager.requestImageForAsset(YourPHAssetVar,
                                  targetSize: CGSizeMake(CGFloat(160), CGFloat(160)),
                                  contentMode: .AspectFill,
                                  options: options,
                                  resultHandler: { (resultThumbnail : UIImage?, info : [NSObject : AnyObject]?) in

                                                   // Assign your thumbnail which is the *resultThumbnail*
                                                  }

此外，您可以使用 PHCachingImageManager 来缓存您的图像以获得更快的 UI 响应：

要使用缓存图像管理器：

  1. 创建一个 PHCachingImageManager 实例。（此步骤替换使用共享的 PHImageManager 实例。）

  2. 使用 PHAsset 类方法来获取您感兴趣的资产。

  3. 要为这些资产准备图像，请调用 startCachingImagesForAssets:targetSize:contentMode:options: 方法，其中包含目标大小、内容模式以及您计划在稍后为每个单独的资产请求图像时使用的选项。

  4. 当您需要单个资产的图像时，调用 requestImageForAsset:targetSize:contentMode:options:resultHandler: 方法，并传递您在准备该资产时使用的相同参数。

如果您请求的图像在已经准备好的图像中，PHCachingImageManager 对象会立即返回该图像。否则，Photos 会按需准备图像并将其缓存以供以后使用。

在我们的示例中：

var phAssetArray : [PHAsset] = []

for i in 0..<assets.count
{
  phAssetArray.append(assets[i] as! PHAsset)
}

let options = PHImageRequestOptions()
options.deliveryMode = .Opportunistic
options.synchronous = false

self.imageManager.startCachingImagesForAssets(phAssetArray,
                                              targetSize: CGSizeMake(CGFloat(160), CGFloat(160)),
                                              contentMode: .AspectFill,
                                              options: options)
于 2016-05-17T08:08:11.980 回答
7

对于 Swift 3.0.1：

func getAssetThumbnail(asset: PHAsset, size: CGFloat) -> UIImage {
    let retinaScale = UIScreen.main.scale
    let retinaSquare = CGSize(width: size * retinaScale, height: size * retinaScale)//(size * retinaScale, size * retinaScale)
    let cropSizeLength = min(asset.pixelWidth, asset.pixelHeight)
    let square = CGRect(x:0, y: 0,width: CGFloat(cropSizeLength),height: CGFloat(cropSizeLength))
    let cropRect = square.applying(CGAffineTransform(scaleX: 1.0/CGFloat(asset.pixelWidth), y: 1.0/CGFloat(asset.pixelHeight)))

    let manager = PHImageManager.default()
    let options = PHImageRequestOptions()
    var thumbnail = UIImage()

    options.isSynchronous = true
    options.deliveryMode = .highQualityFormat
    options.resizeMode = .exact
    options.normalizedCropRect = cropRect

    manager.requestImage(for: asset, targetSize: retinaSquare, contentMode: .aspectFit, options: options, resultHandler: {(result, info)->Void in
        thumbnail = result!
    })
    return thumbnail
}

资源：https ://gist.github.com/lvterry/f062cf9ae13bca76b0c6#file-getassetthumbnail-swift

于 2016-11-11T01:37:37.677 回答
7

斯威夫特 4。

resizeMode, deliveryMode- 可根据用户要求设置。

isNetworkAccessAllowed- 将此设置为“true”以从云中获取图像

imageSize- 所需的图像尺寸

func getImageFromAsset(asset:PHAsset,imageSize:CGSize, callback:@escaping (_ result:UIImage) -> Void) -> Void{

    let requestOptions = PHImageRequestOptions()
    requestOptions.resizeMode = PHImageRequestOptionsResizeMode.fast
    requestOptions.deliveryMode = PHImageRequestOptionsDeliveryMode.highQualityFormat
    requestOptions.isNetworkAccessAllowed = true
    requestOptions.isSynchronous = true
    PHImageManager.default().requestImage(for: asset, targetSize: imageSize, contentMode: PHImageContentMode.default, options: requestOptions, resultHandler: { (currentImage, info) in
        callback(currentImage!)
    })
}
于 2018-06-19T08:45:05.087 回答
7

斯威夫特 5

extension PHAsset {
func getAssetThumbnail() -> UIImage {
    let manager = PHImageManager.default()
    let option = PHImageRequestOptions()
    var thumbnail = UIImage()
    option.isSynchronous = true
    manager.requestImage(for: self,
                         targetSize: CGSize(width: self.pixelWidth, height: self.pixelHeight),
                         contentMode: .aspectFit,
                         options: option,
                         resultHandler: {(result, info) -> Void in
                            thumbnail = result!
                         })
    return thumbnail
    }
}
于 2020-07-21T11:56:25.753 回答
4

问题是 requestImageForAsset 是一个 resultHandler ，并且在您的函数已经打印并返回您期望的值之后，此代码块将在将来发生。我确实进行了更改以向您展示这种情况，并提出了一些简单的解决方案。

func getAssetThumbnail(asset: PHAsset) {
    var retimage = UIImage()
    println(retimage)
    let manager = PHImageManager.defaultManager()
    manager.requestImageForAsset(asset, targetSize: CGSize(width: 100.0, height: 100.0), contentMode: .AspectFit, options: nil, resultHandler: {
    (result, info)->Void in
            retimage = result
      println("This happens after")
      println(retimage)
      callReturnImage(retimage) // <- create this method
    })
    println("This happens before")
}

在Apple 文档中了解有关闭包和完成句柄以及异步函数的更多信息

希望对你有帮助！

于 2015-06-12T21:08:08.443 回答
1

Objective-c 版本的代码基于 dcheng 的答案。

-(UIImage *)getAssetThumbnail:(PHAsset * )asset {

    PHImageRequestOptions *options = [[PHImageRequestOptions alloc]init];
    options.synchronous = true;

    __block UIImage *image;
    [PHCachingImageManager.defaultManager requestImageForAsset:asset targetSize:CGSizeMake(100, 100) contentMode:PHImageContentModeAspectFit options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
        image = result;
    }];
    return image;
  }
于 2018-02-21T06:29:06.953 回答
0

Swift 5 工作功能

func getImageForAsset(asset: PHAsset) -> UIImage {
        let manager = PHImageManager.default
        let option = PHImageRequestOptions()
        var thumbnail = UIImage()
        option.isSynchronous = true
        manager().requestImage(for: asset, targetSize: CGSize(width: 100.0, height: 100.0), contentMode: .aspectFit, options: nil, resultHandler: {(result, info) -> Void in
                thumbnail = result!
        })
        return thumbnail
    }
于 2021-07-25T20:05:32.470 回答