Hi,
I'm trying to execute a task in the background and parsing the output from the
task along the way. However I get the NSTaskDidTerminateNotification before all
the output from the task has been delivered by
NSFileHandleReadCompletionNotification - and I am not able to squeeze much more
(but in some cases a little, but never all the way to the end) out of the
filehandle after the task exits.
Code is what we all want to look at, so here are the interesting bits.
<code start>
App.h:
NSTask *myTask;
NSFileHandle *myFileHandle;
App.m:
- (id) init {
[super init];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(threadPipeReader:)
name:NSFileHandleReadCompletionNotification
object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(threadTaskStopped:)
name:NSTaskDidTerminateNotification
object:nil];
return self;
}
-(void)startMyTask {
NSPipe *pipe = [[NSPipe alloc] init];
myFileHandle = [pipe fileHandleForReading];
[myFileHandle readInBackgroundAndNotify];
myTask = [[NSTask alloc] init];
[myTask setLaunchPath:launchPath];
[myTask setCurrentDirectoryPath:homeDirectory];
[myTask setStandardOutput: pipe];
[myTask setStandardError: pipe];
[myTask setArguments:arguments];
[myTask launch];
}
-(void)threadPipeReader:(NSNotification *)notification {
NSData *data;
data = [[notification userInfo]
objectForKey:NSFileHandleNotificationDataItem];
[ ... do something with data ... ]
[[notification object] readInBackgroundAndNotify];
}
-(void)threadTaskStopped:(NSNotification *)notification {
NSData *data = [myFileHandle availableData];
while ([data length] > 0) {
NSLog(@"got some more: %@", [[NSString alloc]
initWithData:data encoding:NSUTF8StringEncoding]);
NSLog(@"output size: %d", [data length]);
data = [myFileHandle availableData];
}
}
<code end>
I never got the full output in threadPipeReader, but then I tried to fetch the
data in threadTaskStopped - but that only gives some output. Not all the way to
the end either.
I then tried to specify how much data I wanted from myFileHandle in
threadTaskStopped, by doing:
NSData *data = [myFilehandle readDataOfLength:262144];
And then got the output:
got some more: <about 262144 characters of data>
output size: 262144
But then the while-loop exited because myFileHandle was zero length the next
time it got polled. When I don't specify a size, but just asks for
availableData, I get sizes of exactly 16K (16384) multiple times. But never an
odd size - and I can definetely see that the output gets chopped off (sometimes
mid-line) - so I am never able to get the last output from the task.
Can someone help me with this?
Best regards
Rasmus Skaarup
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