ios - Swift:找不到 AVCaptureStillImageOutput 的连接

Question

我正在尝试使用 AVFoundation 制作照片。当我将 obj-c 代码翻译为 swift 来执行此操作时，我的程序在运行我尝试查找 videoConnection 的部分时卡住了。有什么线索吗？

let captureSesion = AVCaptureSession()
var captureDevice : AVCaptureDevice?
let stillImageOutput = AVCaptureStillImageOutput()

captureSesion.sessionPreset = AVCaptureSessionPresetPhoto
    let devices = AVCaptureDevice.devices()
    println(devices)
    for device in devices{
        if device.hasMediaType(AVMediaTypeVideo){
            if device.position == AVCaptureDevicePosition.Back{
                captureDevice = device as? AVCaptureDevice
            }
        }
    }
    if captureDevice != nil{
        var err : NSError? = nil
        captureSesion.addInput(AVCaptureDeviceInput(device: captureDevice, error: &err))

        //preview 
        var previewLayer = AVCaptureVideoPreviewLayer(session: captureSesion)
        self.view.layer.addSublayer(previewLayer)
        previewLayer?.frame = self.view.layer.frame

        var outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG]
        stillImageOutput.outputSettings = outputSettings
        captureSesion.addOutput(stillImageOutput)         
        captureSesion.startRunning()

        //take photo
        var videoConnection : AVCaptureConnection?
        //only have one conniption and debug get stuck here!!
        for connection in self.stillImageOutput.connections{
            for port in connection.inputPorts!{
                if port.mediaType == AVMediaTypeVideo{
                    videoConnection = connection as? AVCaptureConnection
                    break //for ports
                }
            }
            if videoConnection != nil{
                break //for connections
            }
        }
        //Take a photo and show
    }
    }

我成功获取设备和实时预览，但无法获取 stillImageOutput 的视频连接。

[<AVCaptureFigVideoDevice: 0x14d4c660 [Back Camera][com.apple.avfoundation.avcapturedevice.built-in_video:0]>, <AVCaptureFigVideoDevice: 0x14e904d0 [Front Camera][com.apple.avfoundation.avcapturedevice.built-in_video:1]>, <AVCaptureFigAudioDevice: 0x14e8a6d0 [iPod Microphone][com.apple.avfoundation.avcapturedevice.built-in_audio:0]>]

添加了 stilImageOutput 寻找联系 1 (lldb)

Answer 1

好的，我解决了我的问题。帮助别人的锄头。所以问题就在这里:

var videoConnection : AVCaptureConnection?
    //only have one conniption and debug get stuck here!!
    for connection in self.stillImageOutput.connections{
        for port in connection.inputPorts!{
            if port.mediaType == AVMediaTypeVideo{
                videoConnection = connection as? AVCaptureConnection
                break //for ports
            }
        }
        if videoConnection != nil{
            break //for connections
        }
    }//take a photo then

该代码是我将 Objective-C 版本翻译为 swift 的方式。我在网上发现了类似的尝试。然而，很快一切就变得容易多了(但并不明显)。所以这一行解决了这个问题:

if let videoConnection = stillImageOuput.connectionWithMediaType(AVMediaTypeVideo){//take a photo here}