我们有一个使用文件共享的应用程序。设置了 UIFileSharingEnable 等等，这一切似乎都工作正常，但我正在寻找某种关于何时在 iPhone 端添加/删除文件的通知。任何人都可以建议吗？
提前喝彩。
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8401 次
4 回答
23
Apple Developer Forums 上的这个线程可能很有趣，其中建议您在其自己的线程中运行kqueue，跟踪应用程序的 Documents 文件夹。
Apple 技术人员在此处跟进了一些示例代码：
- (void)kqueueFired
{
int kq;
struct kevent event;
struct timespec timeout = { 0, 0 };
int eventCount;
kq = CFFileDescriptorGetNativeDescriptor(self->_kqRef);
assert(kq >= 0);
eventCount = kevent(kq, NULL, 0, &event, 1, &timeout);
assert( (eventCount >= 0) && (eventCount < 2) );
if (eventCount == 1) {
NSLog(@"dir changed");
}
CFFileDescriptorEnableCallBacks(self->_kqRef, kCFFileDescriptorReadCallBack);
}
static void KQCallback(CFFileDescriptorRef kqRef, CFOptionFlags callBackTypes, void *info)
{
ViewController * obj;
obj = (ViewController *) info;
assert([obj isKindOfClass:[ViewController class]]);
assert(kqRef == obj->_kqRef);
assert(callBackTypes == kCFFileDescriptorReadCallBack);
[obj kqueueFired];
}
- (IBAction)testAction:(id)sender
{
#pragma unused(sender)
NSString * docPath;
int dirFD;
int kq;
int retVal;
struct kevent eventToAdd;
CFFileDescriptorContext context = { 0, self, NULL, NULL, NULL };
CFRunLoopSourceRef rls;
docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
assert(docPath != 0);
NSLog(@"%@", docPath);
dirFD = open([docPath fileSystemRepresentation], O_EVTONLY);
assert(dirFD >= 0);
kq = kqueue();
assert(kq >= 0);
eventToAdd.ident = dirFD;
eventToAdd.filter = EVFILT_VNODE;
eventToAdd.flags = EV_ADD | EV_CLEAR;
eventToAdd.fflags = NOTE_WRITE;
eventToAdd.data = 0;
eventToAdd.udata = NULL;
retVal = kevent(kq, &eventToAdd, 1, NULL, 0, NULL);
assert(retVal == 0);
assert(self->_kqRef == NULL);
self->_kqRef = CFFileDescriptorCreate(NULL, kq, true, KQCallback, &context);
assert(self->_kqRef != NULL);
rls = CFFileDescriptorCreateRunLoopSource(NULL, self->_kqRef, 0);
assert(rls != NULL);
CFRunLoopAddSource(CFRunLoopGetCurrent(), rls, kCFRunLoopDefaultMode);
CFRelease(rls);
CFFileDescriptorEnableCallBacks(self->_kqRef, kCFFileDescriptorReadCallBack);
}
于 2010-07-06T18:58:39.770 回答
18
这是使用 Grand Central Dispatch (GCD) 的替代解决方案，它允许您从 NSNotificationCenter 接收文件更改通知：
将这些变量添加到类的接口中：
// Dispatch queue
dispatch_queue_t _dispatchQueue;
// A source of potential notifications
dispatch_source_t _source;
将以下代码添加到实现中：
#define fileChangedNotification @"fileChangedNotification"
// Get the path to the home directory
NSString * homeDirectory = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
// Create a new file descriptor - we need to convert the NSString to a char * i.e. C style string
int filedes = open([homeDirectory cStringUsingEncoding:NSASCIIStringEncoding], O_EVTONLY);
// Create a dispatch queue - when a file changes the event will be sent to this queue
_dispatchQueue = dispatch_queue_create("FileMonitorQueue", 0);
// Create a GCD source. This will monitor the file descriptor to see if a write command is detected
// The following options are available
/*!
* @typedef dispatch_source_vnode_flags_t
* Type of dispatch_source_vnode flags
*
* @constant DISPATCH_VNODE_DELETE
* The filesystem object was deleted from the namespace.
*
* @constant DISPATCH_VNODE_WRITE
* The filesystem object data changed.
*
* @constant DISPATCH_VNODE_EXTEND
* The filesystem object changed in size.
*
* @constant DISPATCH_VNODE_ATTRIB
* The filesystem object metadata changed.
*
* @constant DISPATCH_VNODE_LINK
* The filesystem object link count changed.
*
* @constant DISPATCH_VNODE_RENAME
* The filesystem object was renamed in the namespace.
*
* @constant DISPATCH_VNODE_REVOKE
* The filesystem object was revoked.
*/
// Write covers - adding a file, renaming a file and deleting a file...
_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_VNODE,filedes,
DISPATCH_VNODE_WRITE,
_dispatchQueue);
// This block will be called when teh file changes
dispatch_source_set_event_handler(_source, ^(){
// We call an NSNotification so the file can change can be detected anywhere
[[NSNotificationCenter defaultCenter] postNotificationName:fileChangedNotification object:Nil];
});
// When we stop monitoring the file this will be called and it will close the file descriptor
dispatch_source_set_cancel_handler(_source, ^() {
close(filedes);
});
// Start monitoring the file...
dispatch_resume(_source);
//...
// When we want to stop monitoring the file we call this
//dispatch_source_cancel(source);
// To recieve a notification about the file change we can use the NSNotificationCenter
[[NSNotificationCenter defaultCenter] addObserverForName:fileChangedNotification object:Nil queue:Nil usingBlock:^(NSNotification * notification) {
NSLog(@"File change detected!");
}];
于 2013-12-06T12:02:55.657 回答
4
老问题，但我遇到了这个包含目录监视器的Apple 代码。请注意，它会在添加（或删除）文件时触发；这可能是在操作系统完成写入文件之前。
于 2012-10-06T13:18:22.397 回答
0
它使用 GCD 框架，就像上面 @James 的答案一样，包装在一个组合发布者中，从而产生更简单的客户端代码。
示例用法：
let id = UUID()
let tmpURL = FileManager.default.temporaryDirectory
let url = URL(fileURLWithPath: "\(id)", relativeTo: tmpURL)
let tmp = try! FileDescriptor.open(tmpURL.path, .readOnly, options: .eventOnly)
var received = DispatchSource.FileSystemEvent()
print(received) // prints "FileSystemEvent(rawValue: 0)"
let cancellable = DispatchSource.publish(at: tmp)
.sink { event in
received = event
}
try! FileManager.default.createDirectory(at: url, withIntermediateDirectories: false, attributes: nil)
sleep(1)
print(received) // prints "FileSystemEvent(rawValue: 18)"
cancellable.cancel()
于 2022-01-07T12:06:42.683 回答