On Aug 23, 2009, at 8:01 PM, Kyle Sluder wrote:
On Aug 23, 2009, at 7:42 PM, PCWiz <pcwiz.supp...@gmail.com> wrote:name:@"NSFileHandleReadCompletionNotification"NSFileHandleReadCompletionNotification is the name of a constant, not necessarily its value.
Right, and that was my first thought, too! I've never used NSFileHandle for this purpose, either, so wrote a quick test app to see what would happen. It turns out that the value is the same as the constant in this case, though, and my code below seems to work if I do
date >> /tmp/testfile.txt in Terminal.However, if I open the file with vi and edit/save, the notifications stop coming in. My guess is that vi does an atomic write, so watching the file descriptor breaks when a new file is written instead of just appending to the old one. I've run into problems like that previously, and IIRC you can catch that case with kqueue. Maybe CFFileDescriptor would work also, but I haven't used it yet. You may find that none of the above will work on certain filesystems (e.g., NFS), in which case you probably have to poll the filesystem.
#import <Foundation/Foundation.h>
@interface Reader : NSObject
@end
@implementation Reader
- (void)dataAvailable:(NSNotification *)aNote
{
NSLog(@"%@", aNote);
[[aNote object] readInBackgroundAndNotify];
}
@end
int main (int argc, char const *argv[])
{
NSAutoreleasePool *pool = [NSAutoreleasePool new];
system("/usr/bin/touch /tmp/testfile.txt");
Reader *reader = [Reader new];
NSFileHandle *fh = [NSFileHandle fileHandleForReadingAtPath:@"/
tmp/testfile.txt"];
[[NSNotificationCenter defaultCenter] addObserver:reader
selector:@selector(dataAvailable:)
name:NSFileHandleReadCompletionNotification object:fh];
[fh readInBackgroundAndNotify];
[[NSRunLoop currentRunLoop] addPort:[NSPort port]
forMode:NSDefaultRunLoopMode];
[[NSRunLoop currentRunLoop] run];
[pool drain];
return 0;
}
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