iOS 11 这个方法生成的image为nil，闭包返回不了图片数组

[tianzhilan0]

        imageManeger.requestImage(for: asset, targetSize: bigSize, contentMode: .aspectFit, options: bigOptions, resultHandler: { (image, info) in
            if image != nil{
                model.bigImage = image!
                
                imageManeger.requestImage(for: asset, targetSize: smallSize, contentMode: .aspectFit, options: smallOptions, resultHandler: { (image, info) in
                    if image != nil{
                        model.smallImage = image!
                        
                        imageManeger.requestImageData(for: asset, options: bigOptions, resultHandler: { (data, str, imageOrientation, info) in
                            if data != nil{
                                model.imageData = data!
                                modelArr.append(model)
                                if modelArr.count == photos.count{
                                    DispatchQueue.main.async {
                                        imageData(modelArr.sorted(by: { return $0.order < $1.order }))
                                    }
                                }
                            }
                        })
                    }
                })
            }
        })