sessionDidUpdate - Drag and Drop

sessionDidUpdate.swift

 func dropInteraction(_ interaction: UIDropInteraction, sessionDidUpdate session: UIDropSession) -> UIDropProposal {
        
        let location = session.location(in: self.view)
        let dropOperation: UIDropOperation?
        
        if session.canLoadObjects(ofClass: String.self) {
            
            if dropTextView.frame.contains(location) {
                dropOperation = .copy
            } else if  dropImageView.frame.contains(location) {
                dropOperation = .forbidden
            } else {
                dropOperation = .cancel
            }
        }
        else if session.canLoadObjects(ofClass: UIImage.self) {
            
            if dropImageView.frame.contains(location) {
                dropOperation = .copy
            } else if  dropTextView.frame.contains(location) {
                dropOperation = .forbidden
            } else {
                dropOperation = .cancel
            }
        }
        else {
            dropOperation = .cancel
        }
        
        return UIDropProposal(operation: dropOperation!)
    }