转载：http://blog.csdn.net/enjolras1024/article/details/73471565

初始化图片输入和输出源（AVCaptureDeviceInput，AVCaptureStillImageOutput）

    self.deviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:self.device error:&error];

    self.imageOutput = [[AVCaptureStillImageOutput alloc] init];
    NSDictionary *outputSetting = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecKey, AVVideoCodecJPEG, nil];
    [self.imageOutput setOutputSettings:outputSetting];
    if ([self.session canAddInput:self.deviceInput]) {
        [self.session addInput:self.deviceInput];
    }
    if ([self.session canAddOutput:self.imageOutput]) {
        [self.session addOutput:self.imageOutput];
    }

设置前置摄像头拍照不镜像

// 设置前置摄像头拍照不镜像
AVCaptureDevicePosition currentPosition=[[self.deviceInput device] position];  

AVCaptureConnection *connection = [self.imageOutput connectionWithMediaType:AVMediaTypeVideo];
if (currentPosition == AVCaptureDevicePositionUnspecified || currentPosition == AVCaptureDevicePositionFront) {
     connection.videoMirrored = YES;
} else {
     connection.videoMirrored = NO;
}