xcode NSFileManager 监视目录
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NSFileManager watch directory
提问by Gavy
How would you monitor a directory with NSFileManager?
你将如何监视目录NSFileManager？
I would like to able to detect when a file is deleted/added in my documents directory while my app is running.
我希望能够在我的应用程序运行时检测文件何时被删除/添加到我的文档目录中。
采纳答案by djromero
Look Kernel Queues: An Alternative to File System Eventsin Apple documentation.
There is an example for iOSin AVPlayerDemo (look DirectoryWatcherclass).
查看内核队列：Apple 文档中文件系统事件的替代方案。在 AVPlayerDemo（外观类）中有一个适用于 iOS的示例DirectoryWatcher。
Also, check Directory Monitorblog post.
另外，请查看目录监视器博客文章。
回答by John Stephen
Here's my own version of DirectoryWatcher written in Swift using GCD instead of Mach and using a closure instead of a delegate
这是我自己用 Swift 编写的 DirectoryWatcher 版本，使用 GCD 而不是 Mach 并使用闭包而不是委托
import Foundation
@objc public class DirectoryWatcher : NSObject {
override public init() {
super.init()
}
deinit {
stop()
}
public typealias Callback = (_ directoryWatcher: DirectoryWatcher) -> Void
@objc public convenience init(withPath path: String, callback: @escaping Callback) {
self.init()
if !watch(path: path, callback: callback) {
assert(false)
}
}
private var dirFD : Int32 = -1 {
didSet {
if oldValue != -1 {
close(oldValue)
}
}
}
private var dispatchSource : DispatchSourceFileSystemObject?
@objc public func watch(path: String, callback: @escaping Callback) -> Bool {
// Open the directory
dirFD = open(path, O_EVTONLY)
if dirFD < 0 {
return false
}
// Create and configure a DispatchSource to monitor it
let dispatchSource = DispatchSource.makeFileSystemObjectSource(fileDescriptor: dirFD, eventMask: .write, queue: DispatchQueue.main)
dispatchSource.setEventHandler {[unowned self] in
callback(self)
}
dispatchSource.setCancelHandler {[unowned self] in
self.dirFD = -1
}
self.dispatchSource = dispatchSource
// Start monitoring
dispatchSource.resume()
// Success
return true
}
@objc public func stop() {
// Leave if not monitoring
guard let dispatchSource = dispatchSource else {
return
}
// Don't listen to more events
dispatchSource.setEventHandler(handler: nil)
// Cancel the source (this will also close the directory)
dispatchSource.cancel()
self.dispatchSource = nil
}
}
Use it like Apple's DirectoryWatcher example, something like this:
像 Apple 的 DirectoryWatcher 示例一样使用它，如下所示：
let directoryWatcher = DirectoryWatcher(withPath: "/path/to/the/folder/you/want/to/monitor/", callback: {
print("the folder changed")
})
Destroying the object will stop watching, or you can stop it explicitly
销毁对象将停止观看，或者您可以明确地停止它
directoryWatcher.stop()
It should be compatible with Objective C they way it's written (untested). Using it would be like this:
它应该以它们的编写方式（未经测试）与目标 C 兼容。使用它会是这样的：
DirectoryWatcher *directoryWatcher = [DirectoryWatcher.alloc initWithPath: @"/path/to/the/folder/you/want/to/monitor/" callback: ^(DirectoryWatcher *directoryWatcher) {
NSLog(@"the folder changed")
}];
Stopping it is similar
停止它是相似的
[directoryWatcher stop];
