NSTask waitUntilExit 在越狱 iOS 上挂起应用程序

所以我让 NSTask 运行一个脚本，该脚本生成一个列表，并将其放入我读取的 txt 中。但是，如果我使用当前的代码（如下），则会在 NSTask 完成之前弹出警报，从而导致空白警报。我试过了waitUntilExit但这会使调用此操作的按钮冻结，但 UI 不会自行锁定。

- (void) runSupported {
    stask = [[NSTask alloc] init];
    [stask setLaunchPath:@"/bin/bash"];
    NSString *script;
    script = [[[NSBundle mainBundle] bundlePath] stringByAppendingString:@"/apps.sh"];
    NSArray *sargs = [NSArray arrayWithObjects:script, @"-txt", nil];
    [stask setArguments: sargs];
    [stask launch];

    NSString *apps;
    apps = [NSString stringWithContentsOfFile:@"/var/mobile/supported.txt" encoding:NSUTF8StringEncoding error:nil];
    NSFileManager *fm = [NSFileManager defaultManager];
    if ([fm fileExistsAtPath:apps]) {
        UIAlertView *supported = [[UIAlertView alloc] initWithTitle:@"App List" message:apps delegate:self cancelButtonTitle:@"Ok!" otherButtonTitles:nil];
        [supported show];
        [supported release];
    } else {
        UIAlertView *supported = [[UIAlertView alloc] initWithTitle:@"App List" message:@"Error generating list." delegate:self cancelButtonTitle:@"Ok!" otherButtonTitles:nil];
        [supported show];
        [supported release];
    }
}

知道如何在调用警报之前完成 NSTask 吗？谢谢。

编辑：带有 NSNotification 的代码：

-(IBAction) supported {
    stask = [[NSTask alloc] init];
    [stask setLaunchPath:@"/bin/bash"];
    NSString *script;
    script = [[[NSBundle mainBundle] bundlePath] stringByAppendingString:@"/apps.sh"];
    NSArray *sargs = [NSArray arrayWithObjects:script, @"-txt", nil];
    [stask setArguments: sargs];
    [[NSNotificationCenter defaultCenter] addObserver: self
                                             selector: @selector(taskEnded:)
                                                 name: NSTaskDidTerminateNotification
                                               object: nil]; 
    [stask launch];
}

- (void)taskEnded:(NSNotification *)notification {
    if (stask == [[notification object] terminationStatus]) {
        NSString *apps;
        apps = [NSString stringWithContentsOfFile:@"/var/mobile/supported.txt" encoding:NSUTF8StringEncoding error:nil];
        NSFileManager *fm = [NSFileManager defaultManager];
        if ([fm fileExistsAtPath:apps]) {
            UIAlertView *supported = [[UIAlertView alloc] initWithTitle:@"Apps" message:apps delegate:self cancelButtonTitle:@"Ok!" otherButtonTitles:nil];
            [supported show];
            [supported release];
        } else {
            UIAlertView *supported = [[UIAlertView alloc] initWithTitle:@"Apps" message:@"Error generating list." delegate:self cancelButtonTitle:@"Ok!" otherButtonTitles:nil];
            [supported show];
            [supported release];
        }
    } else {
        NSLog(@"Task failed."); 
    }
}

不要使用waitUntilExit.

问题是如何在任务完成后执行某些操作而不阻塞 UI（或冻结该按钮）。对于所有类似的问题，解决方案是得到通知当任务完成时，并进一步继续（显示警报）以响应该通知。

在本例中，通知是一个名为的 NSNotificationNSTaskDidTerminateNotification。当任务由于任何原因退出时，NSTask 对象会在默认的 NSNotificationCenter 上发布此通知。您可以询问任务的终止状态是什么，以确定它是成功、失败还是崩溃。

也可以看看：通知编程主题 http://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/Notifications/.