Macos NSTask'；实时输出

我有一个PHP脚本，其中包含mutliple

sleep（）

命令。我想用

NSTask

在我的应用程序中执行它。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）：

---

---

我的问题是：如何在打印完这三个单词后立即获取它们？

您可以使用NSFileHandle的

WaitForDataInBackground和Notify方法在脚本将数据写入其输出时接收通知。但是，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，则在任务退出后将收到一个通知

- (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);
    }
}

以下是ughoavgfhw在swift中的回答，以供参考

override func awakeFromNib() {
    // Setup the task
    let task = NSTask()
    task.launchPath = "/usr/bin/php"
    task.arguments = ["-r", "echo \"first\n\"; sleep(1); echo \"second\n\"; sleep(1); echo \"third\n\";"]

    // Pipe the standard out to an NSPipe, and set it to notify us when it gets data
    let pipe = NSPipe()
    task.standardOutput = pipe
    let fh = pipe.fileHandleForReading
    fh.waitForDataInBackgroundAndNotify()

    // Set up the observer function
    let notificationCenter = NSNotificationCenter.defaultCenter()
    notificationCenter.addObserver(self, selector: "receivedData:", name: NSFileHandleDataAvailableNotification, object: nil)

    // You can also set a function to fire after the task terminates
    task.terminationHandler = {task -> Void in
           // Handle the task ending here
    }

    task.launch()
}

func receivedData(notif : NSNotification) {
    // Unpack the FileHandle from the notification
    let fh:NSFileHandle = notif.object as NSFileHandle
    // Get the data from the FileHandle
    let data = fh.availableData
    // Only deal with the data if it actually exists
    if data.length > 1 {
    // Since we just got the notification from fh, we must tell it to notify us again when it gets more data
        fh.waitForDataInBackgroundAndNotify()
        // Convert the data into a string
        let string = NSString(data: data, encoding: NSASCIIStringEncoding)
        println(string!)
    }
}

如果任务在管道中产生大量输出，则此构造是必需的。仅调用
pipe.fileHandleForReading.readDataToEndOfFile（）
将不起作用，因为任务正在等待清空管道，以便在程序等待数据结束时可以写入更多内容。因此，您的程序将挂起。此通知和观察者构造允许异步读取管道，从而防止上述僵局。
我尝试过，但它只记录“first”。“第二个”和“第三个”记录在任务终止时…通过在
-receiveData
中放置额外的
readinbackground和notify
来解决它。谢谢你的主意！经过一段时间的努力，我更新了代码。您需要另一个
waitForDataInBackgroundAndNotify
，而不是
readInBackgroundAndNotify
。使用创建长结果的
find
命令尝试此代码段，该代码段需要额外的
[fh waitForDataInBackgroundAndNotify]
，以获取完整数据。希望这对像我这样的初学者有所帮助。我曾尝试在iOS的Swift（见下文）中使用这段代码，但有趣的是，只有当我的应用程序连接到调试器时，我才能实时收到回电。。。如果我单独运行它，那么在最后我只收到一个调用，而不是一个实时的流。。知道为什么吗？
override func awakeFromNib() {
    // Setup the task
    let task = NSTask()
    task.launchPath = "/usr/bin/php"
    task.arguments = ["-r", "echo \"first\n\"; sleep(1); echo \"second\n\"; sleep(1); echo \"third\n\";"]

    // Pipe the standard out to an NSPipe, and set it to notify us when it gets data
    let pipe = NSPipe()
    task.standardOutput = pipe
    let fh = pipe.fileHandleForReading
    fh.waitForDataInBackgroundAndNotify()

    // Set up the observer function
    let notificationCenter = NSNotificationCenter.defaultCenter()
    notificationCenter.addObserver(self, selector: "receivedData:", name: NSFileHandleDataAvailableNotification, object: nil)

    // You can also set a function to fire after the task terminates
    task.terminationHandler = {task -> Void in
           // Handle the task ending here
    }

    task.launch()
}

func receivedData(notif : NSNotification) {
    // Unpack the FileHandle from the notification
    let fh:NSFileHandle = notif.object as NSFileHandle
    // Get the data from the FileHandle
    let data = fh.availableData
    // Only deal with the data if it actually exists
    if data.length > 1 {
    // Since we just got the notification from fh, we must tell it to notify us again when it gets more data
        fh.waitForDataInBackgroundAndNotify()
        // Convert the data into a string
        let string = NSString(data: data, encoding: NSASCIIStringEncoding)
        println(string!)
    }
}