如何在 AVfoundation 中快速锁定白平衡？

Question

我正在尝试将 iPhone 后置摄像头的白平衡锁定为当前状态，但在将 Objective-C 代码转换为 Swift 时遇到了麻烦。这是 Objective-C 中的代码：

[device setWhiteBalanceMode:AVCaptureWhiteBalanceModeLocked];

这就是我认为 swift 中的代码应该如下所示：

captureDevice.setWhiteBalanceMode(AVCaptureWhiteBalanceMode.Locked)

Xcode 告诉我：

'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()
        }