在iOS 10之前，自定義相機一般使用AVCaptureStillImageOutput實現(xiàn)。但是AVCaptureStillImageOutput在iOS 10以后被棄用了。

62B55636-A7E0-4F36-B88C-FFA28C38749C.png

所以我們來使用AVCapturePhotoOutput來實現(xiàn)自定義簡單相機，AVCapturePhotoOutput 的功能自然會更加強大，不僅支持簡單JPEG圖片拍攝，還支持Live照片和RAW格式拍攝。

使用：
首先初始化：按照需要參數(shù)初始化就行了，和AVCaptureStillImageOutput差別不大。直接上代碼：

    self.session = [AVCaptureSession new];
    [self.session setSessionPreset:AVCaptureSessionPresetHigh];
    
    NSArray *devices = [NSArray new];
    devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *device in devices) {
        if (isBack) {
            if ([device position] == AVCaptureDevicePositionBack) {
                _device = device;
                break;
            }
        }else {
            if ([device position] == AVCaptureDevicePositionFront) {
                _device = device;
                break;
            }
        }
    }
    
    NSError *error;
    self.input = [[AVCaptureDeviceInput alloc] initWithDevice:self.device error:&error];
    if ([self.session canAddInput:self.input]) {
        [self.session addInput:self.input];
    }
    
    self.imageOutput = [[AVCapturePhotoOutput alloc] init];
    NSDictionary *setDic = @{AVVideoCodecKey:AVVideoCodecJPEG};
    _outputSettings = [AVCapturePhotoSettings photoSettingsWithFormat:setDic];
    [self.imageOutput setPhotoSettingsForSceneMonitoring:_outputSettings];
    [self.session addOutput:self.imageOutput];
    self.preview = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
    [self.preview setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    [self.preview setFrame:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
    [self.layer addSublayer:self.preview];
    [self.session startRunning];

實現(xiàn)照片獲取：
AVCaptureStillImageOutput中使用captureStillImageAsynchronouslyFromConnection 在bolck中直接可以獲取到圖片，AVCapturePhotoOutput需要實現(xiàn)AVCapturePhotoCaptureDelegate協(xié)議，在協(xié)議中獲取。
獲取當前屏幕圖片輸出：

[self.imageOutput capturePhotoWithSettings:_outputSettings delegate:self];

實現(xiàn)AVCapturePhotoCaptureDelegate協(xié)議，并在didFinishProcessingPhotoSampleBuffer方法中獲取圖片：

- (void)captureOutput:(AVCapturePhotoOutput *)captureOutput didFinishProcessingPhotoSampleBuffer:(nullable CMSampleBufferRef)photoSampleBuffer previewPhotoSampleBuffer:(nullable CMSampleBufferRef)previewPhotoSampleBuffer resolvedSettings:(AVCaptureResolvedPhotoSettings *)resolvedSettings bracketSettings:(nullable AVCaptureBracketedStillImageSettings *)bracketSettings error:(nullable NSError *)error {
    
    NSData *data = [AVCapturePhotoOutput JPEGPhotoDataRepresentationForJPEGSampleBuffer:photoSampleBuffer previewPhotoSampleBuffer:previewPhotoSampleBuffer];
    UIImage *image = [UIImage imageWithData:data];
    
    UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}

這樣就獲取到圖片了。
最后附Demo