如何在AVfoundation中快速鎖定白平衡？

Question

我試圖鎖定我的iPhone背對相機的白平衡到其當前狀態，但我從轉換Objective-C代碼到swift的麻煩。這是在Objective-C代碼：

[device setWhiteBalanceMode:AVCaptureWhiteBalanceModeLocked]; 

這就是我想在SWIFT代碼應該是這樣的：

captureDevice.setWhiteBalanceMode(AVCaptureWhiteBalanceMode.Locked) 

和Xcode中告訴我：

'AVCaptureDevice' does not have a member named 'setWhiteBalanceMode' 

Answer 1

 if captureDevice.lockForConfiguration(nil) { 
      var gains: AVCaptureWhiteBalanceGains = AVCaptureWhiteBalanceGainsCurrent 
      captureDevice.setWhiteBalanceModeLockedWithDeviceWhiteBalanceGains(gains, completionHandler:nil); 
      captureDevice.unlockForConfiguration() 
     }