Question

使用以下代码我收到此错误：

无法转换类型＆＃39; in out NSError？＆＃39; （又名＆＃39; inout Optional＆＃39;）预期参数类型＆＃39;（）＆＃39;

并且在这行代码中：

if device.lockForConfiguration(&error)

以下是代码的其余部分：

func focusWithMode(focusMode:AVCaptureFocusMode, exposureMode:AVCaptureExposureMode, point:CGPoint, monitorSubjectAreaChange:Bool){

    dispatch_async(self.sessionQueue!, {
        var device: AVCaptureDevice! = self.videoDeviceInput!.device
        var error: NSError? = nil

        if device.lockForConfiguration(&error){
            if device.focusPointOfInterestSupported && device.isFocusModeSupported(focusMode){
                device.focusMode = focusMode
                device.focusPointOfInterest = point
            }
            if device.exposurePointOfInterestSupported && device.isExposureModeSupported(exposureMode){
                device.exposurePointOfInterest = point
                device.exposureMode = exposureMode
            }
            device.subjectAreaChangeMonitoringEnabled = monitorSubjectAreaChange
            device.unlockForConfiguration()
        }

    })

}

Answer 1

InSwift 2错误处理已从NSError输入输出参数更改为try / catch（非例外）。

我认为这是从NSError到try / catch：

的正确转换

func focusWithMode(focusMode:AVCaptureFocusMode, exposureMode:AVCaptureExposureMode, point:CGPoint, monitorSubjectAreaChange:Bool){
    dispatch_async(self.sessionQueue!, {
        var device: AVCaptureDevice! = self.videoDeviceInput!.device
        var error: NSError? = nil

        do {
           try device.lockForConfiguration()
            if device.focusPointOfInterestSupported && device.isFocusModeSupported(focusMode){
                device.focusMode = focusMode
                device.focusPointOfInterest = point
            }
            if device.exposurePointOfInterestSupported && device.isExposureModeSupported(exposureMode){
                device.exposurePointOfInterest = point
                device.exposureMode = exposureMode
            }
            device.subjectAreaChangeMonitoringEnabled = monitorSubjectAreaChange
            device.unlockForConfiguration()
        }
        catch {
            print("Locked error!")
        }
    })
}

Swift 2中的函数错误处理

1 个答案: