如何监视OS X上的文件更改?
答
我无法找到一个简单的例子,所以我参与我想出了以供将来参考:
@interface FileWatch()
@property(assign) dispatch_source_t source;
@end
@implementation FileWatch
@synthesize source;
- (id) initWithPath: (NSString*) path targetQueue: (dispatch_queue_t) queue block: (dispatch_block_t) handler
{
self = [super init];
int descriptor = open([path fileSystemRepresentation], O_EVTONLY);
if (descriptor < 0) {
return nil;
}
[self setSource:dispatch_source_create(DISPATCH_SOURCE_TYPE_VNODE, descriptor, DISPATCH_VNODE_WRITE, queue)];
dispatch_source_set_event_handler(source, handler);
dispatch_source_set_cancel_handler(source, ^{
close(descriptor);
});
dispatch_resume(source);
return self;
}
- (void) dealloc
{
if (source) {
dispatch_source_cancel(source);
dispatch_release(source);
source = NULL;
}
}
@end
答
从我的实际经验,在某些情况下,文件不仅被写入但随后被删除重写(一些plist文件的情况)。然后,您必须稍微调整代码:在ordre中替换文件时再次调用该方法以保持监视。
- (void) myMonitoringMethodWithPath: :(NSString*) path
__block typeof(self) blockSelf = self;
__block dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_VNODE,fildes, DISPATCH_VNODE_DELETE | DISPATCH_VNODE_WRITE | DISPATCH_VNODE_EXTEND | DISPATCH_VNODE_ATTRIB | DISPATCH_VNODE_LINK | DISPATCH_VNODE_RENAME | DISPATCH_VNODE_REVOKE,
queue);
dispatch_source_set_event_handler(source,^
{
unsigned long flags = dispatch_source_get_data(source);
//Do some stuff
if(flags & DISPATCH_VNODE_DELETE)
{
[blockSelf myMonitoringMethodWithPath:path];
}
});
dispatch_source_set_cancel_handler(source, ^(void)
{
close(fildes);
});
dispatch_resume(source);
}
参见:http://*.com/questions/11355144/file-monitoring-using-grand-central-dispatch/11372441#11372441 - 这只是想出最近。 :) – jkh 2012-07-12 19:04:28
会很好,如果你可以描述代码做的评论在那里:/ – 2015-06-07 06:24:35