NSTask的实时输出 [英] NSTask's real-time output

问题描述

我有一个包含多个sleep()命令的PHP脚本.我想在我的应用程序中使用NSTask执行它.我的脚本如下:

I have a PHP script which has mutliple sleep() commands. I would like to execute it in my application with NSTask. My script looks like this:

echo "first\n"; sleep(1); echo "second\n"; sleep(1); echo "third\n";

我可以使用通知异步执行任务:

I can execute my task asynchronously using notifications:

- (void)awakeFromNib {
    NSTask *task = [[NSTask alloc] init];
    [task setLaunchPath: @"/usr/bin/php"];

    NSArray *arguments;
    arguments = [NSArray arrayWithObjects: @"-r", @"echo \"first\n\"; sleep(1); echo \"second\n\"; sleep(1); echo \"third\n\";", nil];
    [task setArguments: arguments];

    NSPipe *p = [NSPipe pipe];
    [task setStandardOutput:p];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(taskExited:) name:NSTaskDidTerminateNotification object:task];

    [task launch];

}

- (void)taskExited:(NSNotification *)notif {
    NSTask *task = [notif object];
    NSData *data = [[[task standardOutput] fileHandleForReading] readDataToEndOfFile];
    NSString *str = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
    NSLog(@"%@",str);
}

我的输出是(当然是2秒钟后):

My output is (after 2 seconds, of course):

2011-08-03 20:45:19.474 MyApp[3737:903] first
second
third

---

我的问题是:这些单词打印后如何立即获得三个单词?

推荐答案

当脚本将数据写入其输出时，可以使用NSFileHandle的waitForDataInBackgroundAndNotify方法接收通知.但是，只有在解释器立即发送字符串的情况下，这才起作用.如果它缓冲输出，则在任务退出后您会收到一条通知.

You can use NSFileHandle's waitForDataInBackgroundAndNotify method to receive a notification when the script writes data to its output. This will only work, however, if the interpreter sends the strings immediately. If it buffers output, you will get a single notification after the task exits.

- (void)awakeFromNib {
    NSTask *task = [[NSTask alloc] init];
    [task setLaunchPath: @"/usr/bin/php"];

    NSArray *arguments;
    arguments = [NSArray arrayWithObjects: @"-r", @"echo \"first\n\"; sleep(1); echo \"second\n\"; sleep(1); echo \"third\n\";", nil];
    [task setArguments: arguments];

    NSPipe *p = [NSPipe pipe];
    [task setStandardOutput:p];
    NSFileHandle *fh = [p fileHandleForReading];
    [fh waitForDataInBackgroundAndNotify];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receivedData:) name:NSFileHandleDataAvailableNotification object:fh];

    [task launch];

}

- (void)receivedData:(NSNotification *)notif {
    NSFileHandle *fh = [notif object];
    NSData *data = [fh availableData];
    if (data.length > 0) { // if data is found, re-register for more data (and print)
        [fh waitForDataInBackgroundAndNotify];
        NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
        NSLog(@"%@" ,str);
    }
}

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