我正在尝试访问相机并在我的 iPad 应用程序中拍照，下面是适用于 swift 1.2 但在 Swift 2 中失败并出现 3 种类型的错误(在 BLOCK 注释中突出显示)的代码。我花了一些时间正在寻找 swift 2 的编写方式，但一无所获。非常感谢任何建议。

import UIKit
import AVFoundation

class PictureController: UIViewController {
    
    let captureSession = AVCaptureSession()
    var previewLayer : AVCaptureVideoPreviewLayer?
    
    // If we find a device we'll store it here for later use
    var captureDevice : AVCaptureDevice?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Do any additional setup after loading the view, typically from a nib.
        captureSession.sessionPreset = AVCaptureSessionPresetHigh
        
        let devices = AVCaptureDevice.devices()
        
        // Loop through all the capture devices on this phone
        for device in devices {
            // Make sure this particular device supports video
            if (device.hasMediaType(AVMediaTypeVideo)) {
                // Finally check the position and confirm we've got the back camera
                if(device.position == AVCaptureDevicePosition.Back) {
                    captureDevice = device as? AVCaptureDevice
                    if captureDevice != nil {
                        print("Capture device found")
                        beginSession()
                    }
                }
            }
        }
        
    }
    
    func focusTo(value : Float) {
        if let device = captureDevice {
            if(device.lockForConfiguration(nil)) { // CALL CAN THROW BUT IS NOT MARKED WITH 'TRY' AND THE ERROR IS NOT HANDLED
// nil IS NOT COMPATIBLE WITH EXPECTED ARGUMENT TYPE '()'
                device.setFocusModeLockedWithLensPosition(value, completionHandler: { (time) -> Void in
                    //
                })
                device.unlockForConfiguration()
            }
        }
    }
    
    let screenWidth = UIScreen.mainScreen().bounds.size.width
    override func touchesBegan(touches: NSSet, withEvent event: UIEvent) { //METHOD DOES NOT OVERRIDE ANY METHOD FROM SUPERCLASS
        let anyTouch = touches.anyObject() as! UITouch
        let touchPercent = anyTouch.locationInView(self.view).x / screenWidth
        focusTo(Float(touchPercent))
    }
    
    override func touchesMoved(touches: NSSet, withEvent event: UIEvent) { //METHOD DOES NOT OVERRIDE ANY METHOD FROM SUPERCLASS
        let anyTouch = touches.anyObject() as! UITouch
        let touchPercent = anyTouch.locationInView(self.view).x / screenWidth
        focusTo(Float(touchPercent))
    }
    
    func configureDevice() {
        if let device = captureDevice {
            device.lockForConfiguration(nil) // CALL CAN THROW BUT IS NOT MARKED WITH 'TRY' AND THE ERROR IS NOT HANDLED
// nil IS NOT COMPATIBLE WITH EXPECTED ARGUMENT TYPE '()'
            device.focusMode = .Locked
            device.unlockForConfiguration()
        }
        
    }
    
    func beginSession() {
        
        configureDevice()
        
        var err : NSError? = nil
        captureSession.addInput(AVCaptureDeviceInput(device: captureDevice, error: &err)) 
// Cannot invoke initializer for type 'AVCaptureDeviceInput' with an argument list of type '(device: AVCaptureDevice?, error: inout NSError?)'
        
        if err != nil {
            print("error: \(err?.localizedDescription)")
        }
        
        previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        self.view.layer.addSublayer(previewLayer)
        previewLayer?.frame = self.view.layer.frame
        captureSession.startRunning()
    }
    
    
}

错误一:调用可以抛出，但是没有标记'try'，错误没有被处理 类型“()”不符合协议(protocol)“BooleanType”

错误 2:方法没有覆盖其父类(super class)中的任何方法 对于 touchesBegan 和 touchesMoved

错误 3:无法使用类型为“(设备:AVCaptureDevice？，错误:inout NSError？)”的参数列表调用类型“AVCaptureDeviceInput”的初始化程序

更新:

所有其他问题均已解决(如果您正在寻找解决方案，请引用评论)，但以下问题除外。

func focusTo(value : Float) {
        if let device = captureDevice {
            if(device.lockForConfiguration()) { // THIS LINE IS THROWING BELOW MENTIONED ERROR
                device.setFocusModeLockedWithLensPosition(value, completionHandler: { (time) -> Void in
                    
                })
                device.unlockForConfiguration()
            }
        }
    }

错误:

Type '()' does not conform to protocol 'BooleanType'

Call can throw, but it is not marked with 'try' and the error is not handled

最佳答案

do {
    try device.lockForConfiguration()
    device.setFocusModeLockedWithLensPosition(value, completionHandler: { (time) -> Void in
                //
    })
    device.unlockForConfiguration()
} catch let error as NSError {
    print(error.code)
}


override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {

}

关于ios - 在 Swift 2 iOS 中访问相机，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32723370/