我收到错误:-whiteBalanceGainscontainanout-of-rangevalue.Red,green,andbluegainsmustbeinthe[1,maxWhiteBalanceGain]range如何确定maxWhiteBalanceGain范围？AVCaptureDevice*device=[AVCaptureDevicedefaultDeviceWithMediaType:AVMediaTypeVideo];AVCaptureWhiteBalanceTemperatureAndTintValuestemperatureAndTint={.temperat