以前，我使用以下内容来发现来自拖放的电子邮件元数据。从Mail.app中删除了电子邮件（/ - 线程）。
if let filenames = draggingInfo.namesOfPromisedFilesDropped(atDestination: URL(fileURLWithPath: destinationDir!)) {
/// TODO: in future implementation Mail might return multiple filenames here.
/// So we will keep this structure to iterate the filenames
//var aPaths: [String] = []
//for _ in filenames {
if let aPath = pb.string(forType: "com.apple.pasteboard.promised-file-url") {
return aPath
}
//}
//return aPaths
}
有点笨拙，但它有效，因为"com.apple.pasteboard.promised-file-url"仅在这些情况下提供。
自10.12以来，API似乎已经发生了变化，看着WWDC2016 talk Apple似乎希望我们现在使用NSFilePromiseReceiver。 我尝试了几种方法，但我无法获得承诺的文件URL。
设定：
class DropzoneView: NSView {
var supportedDragTypes = [
kUTTypeURL as String, // For any URL'able types
"public.url-name", // E-mail title
"public.utf8-plain-text", // Plaintext item / E-mail thread title / calendar event date placeholder
"com.apple.pasteboard.promised-file-content-type", // Calendar event / Web URL / E-mail thread type detection
"com.apple.mail.PasteboardTypeMessageTransfer", // E-mail thread detection
"NSPromiseContentsPboardType", // E-mail thread meta-data
"com.apple.pasteboard.promised-file-url", // E-mail thread meta-data
"com.apple.NSFilePromiseItemMetaData" // E-mail thread meta-data
]
override func viewDidMoveToSuperview() {
var dragTypes = self.supportedDragTypes.map { (type) -> NSPasteboard.PasteboardType in
return NSPasteboard.PasteboardType(type)
} // Experiment:
dragTypes.append(NSPasteboard.PasteboardType.fileContentsType(forPathExtension: "eml"))
dragTypes.append(NSPasteboard.PasteboardType.fileContentsType(forPathExtension: "emlx"))
self.registerForDraggedTypes(dragTypes)
}
}
处理：
extension DropzoneView {
override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
return .copy
}
override func draggingUpdated(_ sender: NSDraggingInfo) -> NSDragOperation {
return .copy
}
override func performDragOperation(_ sender: NSDraggingInfo) -> Bool {
let pasteboard: NSPasteboard = sender.draggingPasteboard()
guard let filePromises = pasteboard.readObjects(forClasses: [NSFilePromiseReceiver.self], options: nil) as? [NSFilePromiseReceiver] else {
return false
}
var files = [Any]()
var errors = [Error]()
let filePromiseGroup = DispatchGroup()
let operationQueue = OperationQueue()
let newTempDirectoryURL = URL(fileURLWithPath: (NSTemporaryDirectory() + (UUID().uuidString) + "/"), isDirectory: true)
do {
try FileManager.default.createDirectory(at: newTempDirectoryURL, withIntermediateDirectories: true, attributes: nil)
}
catch {
return false
}
// Async attempt, either times out after a minute or so (Error Domain=NSURLErrorDomain Code=-1001 "(null)") or gives 'operation cancelled' error
filePromises.forEach({ filePromiseReceiver in
filePromiseGroup.enter()
filePromiseReceiver.receivePromisedFiles(atDestination: newTempDirectoryURL,
options: [:],
operationQueue: operationQueue,
reader: { (url, error) in
Swift.print(url)
if let error = error {
errors.append(error)
}
else if url.isFileURL {
files.append(url)
}
else {
Swift.print("No loadable URLs found")
}
filePromiseGroup.leave()
})
})
filePromiseGroup.notify(queue: DispatchQueue.main,
execute: {
// All done, check your files and errors array
Swift.print("URLs: \(files)")
Swift.print("errors: \(errors)")
})
Swift.print("URLs: \(files)")
return true
}
其他尝试：
// returns nothing
if let filenames = pasteboard.propertyList(forType: NSPasteboard.PasteboardType(rawValue: "com.apple.pasteboard.promised-file-url")) as? NSArray {
Swift.print(filenames)
}
// doesn't result in usable URLs either
if let urls = pasteboard.readObjects(forClasses: [NSPasteboardItem.self /*NSURL.self, ???*/], options: [:]) as? [...
任何指针都会非常感激。
答案 0 :(得分：1)
我设法将文件发送到＆＃34;弹出＆＃34;但我无法得到他们的细节。它立即传输，然后挂起60秒，然后返回错误消息。
也许这是一个线索，但除非被注释掉并设置为true，否则checkExtension方法永远不会返回。
希望这有助于推动行动的发展：
class DropView: NSView
{
var filePath: String?
required init?(coder: NSCoder) {
super.init(coder: coder)
self.wantsLayer = true
self.layer?.backgroundColor = NSColor.red.cgColor
registerForDraggedTypes([NSPasteboard.PasteboardType
.fileNameType(forPathExtension: ".eml"), NSPasteboard.PasteboardType.filePromise])
}
override func draw(_ dirtyRect: NSRect) {
super.draw(dirtyRect)
// Drawing code here.
}
override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
if checkExtension(sender) == true
{
self.layer?.backgroundColor = NSColor.blue.cgColor
return .copy
}
else
{
return NSDragOperation()
}
}
fileprivate func checkExtension(_ drag: NSDraggingInfo) -> Bool
{
return true
// guard let board = drag.draggingPasteboard().propertyList(forType: NSPasteboard.PasteboardType(rawValue: "com.apple.mail.PasteboardTypeMessageTransfer")) as? NSArray,
// let path = board[0] as? String
// else
// {
// return false
// }
//
// let suffix = URL(fileURLWithPath: path).pathExtension
// for ext in self.expectedExt
// {
// if ext.lowercased() == suffix
// {
// return true
// }
// }
// return false
}
override func draggingExited(_ sender: NSDraggingInfo?)
{
self.layer?.backgroundColor = NSColor.gray.cgColor
}
override func draggingEnded(_ sender: NSDraggingInfo)
{
self.layer?.backgroundColor = NSColor.gray.cgColor
}
override func performDragOperation(_ sender: NSDraggingInfo) -> Bool
{
let pasteboard: NSPasteboard = sender.draggingPasteboard()
guard let filePromises = pasteboard.readObjects(forClasses: [NSFilePromiseReceiver.self], options: nil) as? [NSFilePromiseReceiver] else {
return false
}
print ("Files dropped")
var files = [URL]()
let filePromiseGroup = DispatchGroup()
let operationQueue = OperationQueue()
let destURL = URL(fileURLWithPath: "/Users/andrew/Temporary", isDirectory: true)
print ("Destination URL: \(destURL)")
filePromises.forEach ({ filePromiseReceiver in
print (filePromiseReceiver)
filePromiseGroup.enter()
filePromiseReceiver.receivePromisedFiles(atDestination: destURL,
options: [:],
operationQueue: operationQueue,
reader:
{ (url, error) in
print ("Received URL: \(url)")
if let error = error
{
print ("Error: \(error)")
}
else
{
files.append(url)
}
print (filePromiseReceiver.fileNames, filePromiseReceiver.fileTypes)
filePromiseGroup.leave()
})
})
filePromiseGroup.notify(queue: DispatchQueue.main,
execute:
{
print ("Files: \(files)")
print ("Done")
})
return true
}
}
这个输出有点奇怪。 url变量aways重复我传入的目录的名称，例如
Files dropped
Destination URL: file:///Users/andrew/Temporary/
<NSFilePromiseReceiver: 0x6000000a1aa0>
** one minute gap **
Received URL: file:///Users/andrew/Temporary/Temporary/
Error: Error Domain=NSURLErrorDomain Code=-1001 "(null)"
["Temporary"] ["com.apple.mail.email"]
Files: []
Done
答案 1 :(得分：1)
我在尝试将承诺的文件接收到无效的目标网址时看到此错误。
就我而言，我在使用 Ole Begemann's Temporary File Helper 时不小心让它超出了范围，这导致在复制任何内容之前删除了目录。
receivePromisedFiles 在长时间等待后给了我 -1001 超时错误，但它仍然传递了一个根据我的输入应该正确的 URL。显然那个位置没有文件。
当我更改为有效的 url 时，一切都按预期工作。可能值得检查沙盒问题等。
Apple 现在在此处的 File Promises 部分提供了一些有用的示例项目： https://developer.apple.com/documentation/appkit/documents_data_and_pasteboard