macos - NSTask的实时输出

Question

我有一个 PHP 脚本，其中有多个 sleep() 命令。我想在我的应用程序中使用 NSTask 执行它。我的脚本如下所示:

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

我可以使用通知异步执行我的任务:

- (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 秒后):

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

<小时/>

我的问题是:如何在打印后立即获得这三个单词？

Answer 1

您可以使用 NSFileHandle 的 waitForDataInBackgroundAndNotify 方法在脚本将数据写入其输出时接收通知。然而，只有当解释器立即发送字符串时，这才有效。如果它缓冲输出，您将在任务退出后收到一条通知。

- (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);
    }
}