macos -拖动字符串到NSStatusItem

Question

我试图检测一个字符串何时被拖到NSStatusItem上。下面是我的代码在AppDelegate中的实现:

func applicationDidFinishLaunching(_ aNotification: Notification) {
if let button = statusItem.button {
button.image = NSImage(named:NSImage.Name("StatusBarButtonImage"))
button.action = #selector(menubarAction(_:))
button.sendAction(on: [.leftMouseUp, .rightMouseUp])
button.window?.registerForDraggedTypes([.string ])
button.window?.delegate = self
}
}

这是我的NSWindow委托调用

extension AppDelegate:NSWindowDelegate{

func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation{
NSApplication.shared.activate(ignoringOtherApps: true )
return .copy
}

func performDragOperation(_ sender: NSDraggingInfo) -> Bool{
NSApplication.shared.activate(ignoringOtherApps: true )
return true
}
}

然而，当一个字符串被拖到NSStatusItem上时，这些委托不会被调用。我知道拖拽被检测为:

applicationDidBecomeActive(_ notification: Notification)

被调用。为什么我的委托没有被调用。
谢谢
Reza

Answer 1

draggingEntered和performDragOperation为协议NSDraggingDestination的方法。如果类不采用协议，Swift不会调用协议方法。AppDelegate必须采用NSDraggingDestination

extension AppDelegate: NSWindowDelegate {
}
extension AppDelegate: NSDraggingDestination {

func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation{
NSApplication.shared.activate(ignoringOtherApps: true )
return .copy
}

func performDragOperation(_ sender: NSDraggingInfo) -> Bool{
NSApplication.shared.activate(ignoringOtherApps: true )
return true
}
}