小编Dam*_*ian的帖子

在Xcode中设置前置摄像头.我怎样才能做到这一点？在Xcode中设置前置摄像头.

AVCaptureSession *session = [AVCaptureSession new];
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone)
    [session setSessionPreset:AVCaptureSessionPreset640x480];
else
    [session setSessionPreset:AVCaptureSessionPresetPhoto];

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
require( error == nil, bail );

isUsingFrontFacingCamera = NO;
if ( [session canAddInput:deviceInput] )
    [session addInput:deviceInput];

stillImageOutput = [AVCaptureStillImageOutput new];
[stillImageOutput addObserver:self forKeyPath:@"capturingStillImage" options:NSKeyValueObservingOptionNew context:AVCaptureStillImageIsCapturingStillImageContext];
if ( [session canAddOutput:stillImageOutput] )
    [session addOutput:stillImageOutput];

我存档项目时收到错误消息.怎么解决？

static let litersPerUSGallon = NSDecimalNumber(mantissa:UInt64(3785411784), exponent: -9, isNegative:false)
static let litersPerImperialGallon = NSDecimalNumber(mantissa:UInt64(454609), exponent: -5, isNegative:false)
static let kilometersPerStatuteMile = NSDecimalNumber(mantissa:UInt64(1609344), exponent: -6, isNegative:false)
static let kilometersPerLiterToMilesPerUSGallon = NSDecimalNumber(mantissa:UInt64(2352145833), exponent: -9, isNegative:false)
static let kilometersPerLiterToMilesPerImperialGallon = NSDecimalNumber(mantissa:UInt64(2737067636), exponent: -9, isNegative:false)
static let litersPer100KilometersToMilesPer10KUSGallon = NSDecimalNumber(mantissa:UInt64(425170068027), exponent: -10, isNegative:false)
static let litersPer100KilometersToMilesPer10KImperialGallon = NSDecimalNumber(mantissa:UInt64(353982300885), exponent: -10, isNegative:false)