UIDropInteractionDelegate performDrop不被调用吗? [英] UIDropInteractionDelegate performDrop not called?

问题描述

我正在尝试构建一个简单的测试应用程序以学习拖放API.对于这个问题，我只关注Drop场景.我有一个空白的View Controller，同时打开了safari应用程序(多任务)，然后尝试将Google的图片拖到View Controller的视图上.

I am trying to build a simple test app to learn Drag and Drop APIs. For this question I am focusing only on the Drop scenario. I have a blank View Controller, with the safari app open (multitasking) I then try to drag an image from google onto the View Controller's view.

我可以将图像从野生动物园拖到应用程序的View Controller中，但是当我放开手时，以下调用将永远不会被调用:

I can drag the image from safari to my app's View Controller, but when I let go, this call below is never called:

func dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession)

这是我的代码:

class EditTestVC: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        view.addInteraction(UIDropInteraction(delegate: self))
    }

}

extension EditTestVC:UIDropInteractionDelegate {

    func dropInteraction(_ interaction: UIDropInteraction, canHandle session: UIDropSession) -> Bool { // 1
        print("canHandle session: \(session)")
        return true
//        return session.canLoadObjects(ofClass: UIImage.self)
    }

    func dropInteraction(_ interaction: UIDropInteraction, sessionDidUpdate session: UIDropSession) -> UIDropProposal { // 2
        print("sessionDidUpdate session: \(session)")
        return UIDropProposal(operation: .copy)
    }

    func dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession) {
        print("performDrop session: \(session)")
    }


}

最上面的两个方法称为:

The top two methods are called, this one:

func dropInteraction(_ interaction: UIDropInteraction, canHandle session: UIDropSession) -> Bool

和这个:

func dropInteraction(_ interaction: UIDropInteraction, sessionDidUpdate session: UIDropSession) -> UIDropProposal

所以，我试图弄清楚为什么这样一个:

So, I am trying to figure out why this one:

func dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession)

从不叫.

有什么建议吗?

推荐答案

我刚刚测试了您的代码，所有方法都被调用.一定是小故障.

I just tested your code and all methods are getting called. It must be a glitch.

故障排除步骤:

删除应用程序->重新启动模拟器->清理构建文件夹->重建->运行.您也可以先尝试在其他模拟器中运行以节省时间.

Delete app -> Restart the simulator -> Clean build folder -> Rebuild -> Run. You can also try running in different simulator first to save time.

这篇关于UIDropInteractionDelegate performDrop不被调用吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！