Transferable 简介

4:36 - Declaring a custom content type

import UniformTypeIdentifiers

// also declare the content type in the Info.plist
extension UTType {
    static var profile: UTType = UTType(exportedAs: "com.example.profile")
}

5:10 - PasteButton interface

import SwiftUI

struct Profile {
    private var funFacts: [String] = []
    mutating func addFunFacts(_ newFunFacts: [String]) {
        funFacts.append(newFunFacts)
    }
}

struct PasteButtonView: View {
    @State var profile = Profile()
    var body: some View {
        PasteButton(payloadType: String.self) { funFacts in
            profile.addFunFacts(funFacts)
        }
    }
}

5:19 - Drag and Drop

import SwiftUI

struct PortraitView: View {
    @State var portrait: Image
    var body: some View {
        portrait
            .cornerRadius(8)
            .draggable(portrait)
            .dropDestination(payloadType: Image.self) { (images: [Image], _) in
                if let image = images.first {
                    portrait = image
                    return true
                }
                return false
            }
    }
}

5:27 - Sharing

import SwiftUI

struct Profile {
    var name: String
}

struct ProfileView: View {
    @State private var portrait: Image
    var model: Profile

    var body: some View {
        VStack {
            portrait
            Text(model.name)
        }
        .toolbar {
            ShareLink(item: portrait, preview: SharePreview(model.name))
        }
    }
}

6:34 - Profile structure

import Foundation

struct Profile: Codable {
    var id: UUID
    var name: String
    var bio: String
    var funFacts: [String]
    var video: URL?
    var portrait: URL?
}

7:31 - CodableRepresentation

import CoreTransferable
import UniformTypeIdentifiers

struct Profile: Codable {
    var id: UUID
    var name: String
    var bio: String
    var funFacts: [String]
    var video: URL?
    var portrait: URL?
}

extension Profile: Codable, Transferable {
    static var transferRepresentation: some TransferRepresentation {
        CodableRepresentation(contentType: .profile)
    }
}

// also declare the content type in the Info.plist
extension UTType {
    static var profile: UTType = UTType(exportedAs: "com.example.profile")
}

8:30 - DataRepresentation

import CoreTransferable
import UniformTypeIdentifiers

struct ProfilesArchive {
    init(csvData: Data) throws { }
    func convertToCSV() throws -> Data { Data() }
}

extension ProfilesArchive: Transferable {
    static var transferRepresentation: some TransferRepresentation {
        DataRepresentation(contentType: .commaSeparatedText) { archive in
            try archive.convertToCSV()
        } importing: { data in
            try ProfilesArchive(csvData: data)
        }
    }
}

9:14 - FileRepresentation

import CoreTransferable

struct Video: Transferable {
    let file: URL
    static var transferRepresentation: some TransferRepresentation {
        FileRepresentation(contentType: .mpeg4Movie) { 
            SentTransferredFile($0.file)
        } importing: { received in
            let destination = try Self.copyVideoFile(source: received.file)
            return Self.init(file: destination)
        }
    }
  
    static func copyVideoFile(source: URL) throws -> URL {
        let moviesDirectory = try FileManager.default.url(
            for: .moviesDirectory, in: .userDomainMask,
            appropriateFor: nil, create: true
        )
        var destination = moviesDirectory.appendingPathComponent(
            source.lastPathComponent, isDirectory: false)
        if FileManager.default.fileExists(atPath: destination.path) {
            let pathExtension = destination.pathExtension
            var fileName = destination.deletingPathExtension().lastPathComponent
            fileName += "_\(UUID().uuidString)"
            destination = destination
                .deletingLastPathComponent()
                .appendingPathComponent(fileName)
                .appendingPathExtension(pathExtension)
        }
        try FileManager.default.copyItem(at: source, to: destination)
        return destination
    }
}

10:05 - ProxyRepresentation

import CoreTransferable
import UniformTypeIdentifiers

struct Profile: Codable {
    var id: UUID
    var name: String
    var bio: String
    var funFacts: [String]
    var video: URL?
    var portrait: URL?
}

extension Profile: Transferable {
    static var transferRepresentation: some TransferRepresentation {
        CodableRepresentation(contentType: .profile)
        ProxyRepresentation(exporting: \.name)
    }
}

// also declare the content type in the Info.plist
extension UTType {
    static var profile: UTType = UTType(exportedAs: "com.example.profile")
}

11:34 - Proxy and file representations

import CoreTransferable

struct Video: Transferable {
    let file: URL
    static var transferRepresentation: some TransferRepresentation {
        FileRepresentation(contentType: .mpeg4Movie) { SentTransferredFile($0.file) }
           importing: { received in
               let copy = try Self.copyVideoFile(source: received.file)
               return Self.init(file: copy) }
        ProxyRepresentation(exporting: \.file)
  }

    static func copyVideoFile(source: URL) throws -> URL {
        let moviesDirectory = try FileManager.default.url(
            for: .moviesDirectory, in: .userDomainMask,
            appropriateFor: nil, create: true
        )
        var destination = moviesDirectory.appendingPathComponent(
            source.lastPathComponent, isDirectory: false)
        if FileManager.default.fileExists(atPath: destination.path) {
            let pathExtension = destination.pathExtension
            var fileName = destination.deletingPathExtension().lastPathComponent
            fileName += "_\(UUID().uuidString)"
            destination = destination
                .deletingLastPathComponent()
                .appendingPathComponent(fileName)
                .appendingPathExtension(pathExtension)
        }
        try FileManager.default.copyItem(at: source, to: destination)
        return destination
    }
}

12:57 - Exporting condition

import CoreTransferable
import UniformTypeIdentifiers

struct ProfilesArchive {
    var supportsCSV: Bool { true }
    init(csvData: Data) throws {  }
    func convertToCSV() throws -> Data { Data() }
}

extension ProfilesArchive: Transferable {
    static var transferRepresentation: some TransferRepresentation {
        DataRepresentation(contentType: .commaSeparatedText) { archive in
            try archive.convertToCSV()
        } importing: { data in
            try Self(csvData: data)
        }
        .exportingCondition { $0.supportsCSV }
    }
}