Question

我看到关于使用iPhone 4 / 4s闪光灯作为手电筒的帖子。我发现它非常有用，我试图用它来快速打开/关闭LED，以便将它用作莫尔斯变送器，但它不起作用。根据我使用的代码，这个用途太慢了：

-(void)toggleTorch
{
    AVCaptureDevice *_device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    // check if the device has the torch
    if([_device hasTorch] && [_device hasFlash])
    {
        if (_device.torchMode == AVCaptureTorchModeOff) 
        {            
            // we want to turn the torch on
            AVCaptureDeviceInput *_flashInput = [AVCaptureDeviceInput deviceInputWithDevice:_device error:nil];
            AVCaptureVideoDataOutput *_output = [[AVCaptureVideoDataOutput alloc] init];

            AVCaptureSession *_session = [[AVCaptureSession alloc] init];
            [_session beginConfiguration];
            [_device lockForConfiguration:nil];

             [_session addInput:_flashInput];
             [_session addOutput:_output];

            [_device unlockForConfiguration];

            //[_output release];
            [_session commitConfiguration];
            [_session startRunning];

            [self setTorchSession:_session];
        }
        else 
        {            
            [self.torchSession stopRunning];
        }
    }
}

// turn the torch on/off
-(IBAction)toggleTorch:(id)sender
{
    AVCaptureDevice *_device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    // check if the device has the torch
    if([_device hasTorch] && [_device hasFlash])
    {
        if (_device.torchMode == AVCaptureTorchModeOff) 
        {
            [self switchTorchON];
        }
        else 
        {
            [self switchTorchOFF];
        }
    }
}

-(void)switchTorchON
{
    [NSThread detachNewThreadSelector:@selector(changeSwitchImage) 
                             toTarget:self 
                           withObject:nil];

    Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
    if (captureDeviceClass != nil) {

        AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

        [device lockForConfiguration:nil];

        [device setTorchMode:AVCaptureTorchModeOn];
        [device setFlashMode:AVCaptureFlashModeOn];

        [device unlockForConfiguration];

    }
}
-(void)switchTorchOFF
{
    [NSThread detachNewThreadSelector:@selector(changeSwitchImage) 
                             toTarget:self 
                           withObject:nil];
    // test if this class even exists to ensure flashlight is turned on ONLY for iOS 4 and above
    Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
    if (captureDeviceClass != nil) {

        AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

        [device lockForConfiguration:nil];

        [device setTorchMode:AVCaptureTorchModeOff];
        [device setFlashMode:AVCaptureFlashModeOff];

        [device unlockForConfiguration];

    }   
}

-(IBAction)toggleSOS:(id)sender
{
    // morse SOS: ...---...
    [self switchTorchON];
    [self switchTorchOFF];

    [self switchTorchON];
    [self switchTorchOFF];

    [self switchTorchON];
    [self switchTorchOFF];

}

当我按下sos按钮时，我看到一个闪光灯。有人可以帮帮我吗？

Answer 1

您使用的方法确实很慢。请改用this Stackoverflow链接中的方法。

实际的开/关代码是：

[self.myDevice lockForConfiguration:nil];
[self.myDevice setTorchMode:AVCaptureTorchModeOn];
[self.myDevice setFlashMode:AVCaptureFlashModeOn];
[self.myDevice unlockForConfiguration];

但请确保myDevice已初始化（请参阅链接）

使用NStimer实现它，以创建您想要的闪存长度。

编辑：

抱歉，我认为您试图收集摩尔斯电码输入，然后指示闪光灯切换NSTimer。

尝试使用NSTimer或睡眠线程以增加闪烁间隔之间的时间。它可能执行得太快，无法处理实际的闪存组件。在SOS方法上试一试，以便于测试。

Answer 2

我尝试使用NSTimer，但它没有用。
最后，我使用performSelector:withObject:afterDelay:

解决了问题

使用iPhone 4 / 4s作为莫尔斯发射器

2 个答案: