//渡したい画像
class ImageActivityItem:NSObject,UIActivityItemSource{
    var image:UIImage?
    override init(){
        super.init()
    }
    convenience init(_ image:UIImage?){
        self.init()
        self.image = image
    }

    func activityViewControllerPlaceholderItem(_ activityViewController: UIActivityViewController) -> Any {
        return image ?? UIImage()
    }

    func activityViewController(_ activityViewController: UIActivityViewController, itemForActivityType activityType: UIActivityType?) -> Any? {
        if activityType?.rawValue == "com.burbn.instagram.shareextension"{
            //例えばここで真四角に切り取り処理をするとか。
            let ref = image!.cgImage!.cropping(to: CGRect(x:0,y:0,width:100,height:100))
            let cropImage = UIImage(cgImage: ref!, scale: self.image!.scale, orientation: image!.imageOrientation)
            return cropImage
        }
        return image
    }

}