【发布时间】：2015-12-19 19:33:15
【问题描述】：
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 的代码，但在 Swift 2 中因 3 种类型的错误而失败（在 BLOCK cmets 下方突出显示）。我花了时间寻找 swift 2 的写作方式，但没有得到任何地方。任何建议都非常感谢。
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1：调用可以抛出，但是没有标记'try'并且错误没有被处理 类型 '()' 不符合协议 'BooleanType'
错误 2：方法没有覆盖其超类中的任何方法 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：
所有其他问题都已修复（如果您正在寻找解决方案，请参考 cmets），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：
类型“()”不符合协议“BooleanType”
调用可以抛出，但是没有标记'try'并且错误没有处理
【问题讨论】：
-
你试过运行 Swift 2 迁移器吗？
-
error3：只需添加尝试！在 AVCaptureDeviceInput 前面删除最后一个参数“, error: &err”
-
@AaronBrager 迁移器没有针对这些错误显示任何建议。当我尝试编译和构建时，编译器会突出显示出现上述错误的行。
-
@Rao 简单修复 如果您不想处理错误，那么对于 Xcode 7 的所有错误参数都是这样，否则您需要实现 do { try } catch { print(error)}
-
如果您仍需要帮助，请告诉我，以便我重新提出问题
标签： ios swift swift2 xcode7 avcapturesession