工作之余，研究了一下相机与相册的自定义，在这里整理成篇仅供参考学习，希望可以给大家带来些许帮助，也期待大家的批评指正。
GIF 示例:

ccpcamera.gif

DEMO下载地址：https://github.com/IMCCP/CCPCustomCamera

iOS开发中调用相机来获取照片时，如果对相机样式没有过多的要求，通常我们会调用UIImagePickerController这个系统封装好的控件。但是有时UIImagePickerController无法满足项目的需求，例如我们需要自定义的相机样式，此时则需要自己构造一个相机控件，因此需要使用AVFoundation框架进行相机的自定义。

首先导入 AVFoundation.framework

#import <AVFoundation/AVFoundation.h>

一、创建相机相关的属性

/**
 *  用来获取相机设备的一些属性
 */
@property (nonatomic,strong)AVCaptureDevice *device;

/**
 *  用来执行输入设备和输出设备之间的数据交换
 */
@property(nonatomic,strong)AVCaptureSession * session;

/**
 *  输入设备，调用所有的输入硬件，例如摄像头、麦克风
 */
@property (nonatomic,strong)AVCaptureDeviceInput *deviceInput;

/**
 *  照片流输出，用于输出图像
 */
@property (nonatomic,strong)AVCaptureStillImageOutput *imageOutput;

/**
 *  镜头扑捉到的预览图层
 */
@property (nonatomic,strong)AVCaptureVideoPreviewLayer *previewLayer;

/**
 *  session通过AVCaptureConnection连接AVCaptureStillImageOutput进行图片输出
 */
@property (nonatomic,strong) AVCaptureConnection *connection;

#以下属性只是在本DEMO中有用到，大家可以按照自己项目的需求进行添加。
/**
 *  记录屏幕的旋转方向
 */
@property (nonatomic,assign) UIDeviceOrientation deviceOrientation;

/**
 *  给自定义相机添加（UIPinchGestureRecognizer）手势 ->记录开始的缩放比例
 */
@property(nonatomic,assign)CGFloat beginGestureScale;

/**
 *  记录最后的缩放比例
 */
@property(nonatomic,assign)CGFloat effectiveScale;

/**
 *  自定义闪光灯功能 ->闪光灯按钮
 */
@property(nonatomic,weak)UIButton *lightButton;

/**
 *  闪光灯状态
 */
@property (nonatomic,assign) NSInteger lightCameraState;

/**
 *  遮照View,主要用来自定义相机界面的显示效果
 */
@property (nonatomic,weak) CCPCameraView *caramView;

二、相机界面的布局

1.图片示意图

gif.png

2.布局代码

- (void) makeUI {
    //设置图层的frame
    CGFloat ScreenW = self.view.frame.size.width;
    CGFloat ScreenH = self.view.frame.size.height;
    #顶部视图
    UIView *headView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, ScreenW, 40)];
    headView.backgroundColor = [UIColor blackColor];
    //返回按钮
    UIButton *backButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 60, 40)];
    [backButton addTarget:self action:@selector(clickBackButton) forControlEvents:UIControlEventTouchUpInside];
    [backButton setTitle:@"返回" forState:UIControlStateNormal];
    [backButton setTintColor:[UIColor whiteColor]];
    [headView addSubview:backButton];
    //切换镜头按钮
    UIButton *changeButton = [[UIButton alloc] initWithFrame:CGRectMake(ScreenW - 60, 0, 60, 40)];
    [changeButton addTarget:self action:@selector(clickchangeButton) forControlEvents:UIControlEventTouchUpInside];
    [changeButton setImage:[UIImage imageNamed:@"camera-switch"] forState:UIControlStateNormal];
    [headView addSubview:changeButton];
    //闪光灯
    UIButton *lightButton = [[UIButton alloc] initWithFrame:CGRectMake(ScreenW / 2 - 30, 0, 60, 40)];
    [lightButton addTarget:self action:@selector(clickLightButton:) forControlEvents:UIControlEventTouchUpInside];
    [lightButton setImage:[UIImage imageNamed:@"flashOffIcon"] forState:UIControlStateNormal];
    self.lightButton = lightButton;
    [headView addSubview:lightButton];
    [self.view addSubview:headView];
    
   #中部相机视图
    NSError *error;
    //创建会话层
    self.device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    //初始化session
    self.session = [[AVCaptureSession alloc] init];
    if ([self.session canSetSessionPreset:AVCaptureSessionPresetPhoto]) {
        self.session.sessionPreset = AVCaptureSessionPresetPhoto;
    }
    //初始化输入设备
    self.deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:&error];
    //初始化照片输出对象
    self.imageOutput = [[AVCaptureStillImageOutput alloc] init];
    //输出设置,AVVideoCodecJPEG 输出jpeg格式图片
    NSDictionary * outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey, nil];
    [self.imageOutput setOutputSettings:outputSettings];
    //判断输入输出设备是否可用
    if ([self.session canAddInput:self.deviceInput]) {
        [self.session addInput:self.deviceInput];
    }
    if ([self.session canAddOutput:self.imageOutput]) {
        [self.session addOutput:self.imageOutput];
    }
    //初始化预览图层
    self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
    
    /** 设置图层的填充样式
     *  AVLayerVideoGravityResize,       // 非均匀模式。两个维度完全填充至整个视图区域
     AVLayerVideoGravityResizeAspect,  // 等比例填充，直到一个维度到达区域边界
     AVLayerVideoGravityResizeAspectFill, // 等比例填充，直到填充满整个视图区域，其中一个维度的部分区域会被裁剪
     */
    self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    self.previewLayer.frame = CGRectMake(0, 40,ScreenW, ScreenW * 4 / 3);
    [self.view.layer insertSublayer:self.previewLayer atIndex:0];
    CGFloat previewLayerY = CGRectGetMaxY(self.previewLayer.frame);
    //遮照view
    CCPCameraView *caramView = [[CCPCameraView alloc] init];
    caramView.frame = self.previewLayer.frame;
    caramView.backgroundColor = [UIColor clearColor];
    caramView.delegate = self;
    self.caramView = caramView;
    //添加捏合手势
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinchGesture:)];
    pinch.delegate = self;
    [caramView addGestureRecognizer:pinch];
    [self.view addSubview:caramView];
  
    #底部视图
    CGRect rect = CGRectMake(0, previewLayerY , ScreenW, ScreenH - previewLayerY);
    UIView *bottomView = [[UIView alloc] initWithFrame:rect];
    bottomView.backgroundColor = [UIColor blackColor];
    [self.view addSubview:bottomView];
    UIButton *button = [[UIButton alloc] init];
    [button setImage:[UIImage imageNamed:@"btn_prisma_takephoto"] forState:UIControlStateNormal];
    button.frame = CGRectMake(0, 0, 60, 60);
    button.centerX = bottomView.centerX;
    button.centerY = bottomView.height / 2;
    [button addTarget:self action:@selector(clickPHOTO) forControlEvents:UIControlEventTouchUpInside];
    [bottomView addSubview:button];
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(15, 0, bottomView.height/2, bottomView.height/2)];
    imageView.layer.cornerRadius = 1.0f;
    imageView.layer.masksToBounds = YES;
    imageView.centerY = bottomView.height / 2;
    imageView.backgroundColor = [UIColor redColor];
    [bottomView addSubview:imageView];
    self.bottomImageView = imageView;
}

三、主要功能介绍

1.拍照按钮
这里需要注意的是拍照完成后的照片显示的方向问题。
屏幕的方向大致可以分为以下6中：
home键盘朝下/home键朝右/home键朝上/home键朝左，还有两种就是屏幕朝上和屏幕朝下。因此需要根据不同屏幕方向进行照片的旋转，否则照片的显示将会出现问题，解决方法见下文介绍。

- (void)clickPHOTO {
    self.connection = [self.imageOutput connectionWithMediaType:AVMediaTypeVideo];
    /**
     *   UIDeviceOrientation 获取机器硬件的当前旋转方向
     需要注意的是如果手机手动锁定了屏幕，则不能判断旋转方向
     */
    UIDeviceOrientation curDeviceOrientation = [[UIDevice currentDevice] orientation];
    NSLog(@"-------%ld",(long)curDeviceOrientation);
    /**
     *  UIInterfaceOrientation 获取视图的当前旋转方向
     需要注意的是只有项目支持横竖屏切换才能监听到旋转方向
     */
    UIInterfaceOrientation sataus=[UIApplication sharedApplication].statusBarOrientation;
    NSLog(@"+++++++%ld",(long)sataus);
    /**
     *  为了实现在锁屏状态下能够获取屏幕的旋转方向，这里通过使用 CoreMotion 框架（加速计）进行屏幕方向的判断
     self.deviceOrientation = [MotionOrientation sharedInstance].deviceOrientation
     在这里用到了第三方开源框架 MotionOrientation 对作者表示衷心的感谢
     框架地址： GitHub:https://github.com/tastyone/MotionOrientation
     */
    NSLog(@"********%ld",(long)self.deviceOrientation);
    //获取输出视图的展示方向
    AVCaptureVideoOrientation avcaptureOrientation = [self avOrientationForDeviceOrientation: self.deviceOrientation];
    [self.connection setVideoOrientation:avcaptureOrientation];
    [self.connection setVideoScaleAndCropFactor:self.effectiveScale];
    [self.imageOutput captureStillImageAsynchronouslyFromConnection:self.connection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
        NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
        //原图
        UIImage *image = [UIImage imageWithData:jpegData];
        #pragma mark - 图片的截取,通过对不同属性的设置获取目标的截图样式
        if (self.isCanCut) {
            TOCropViewController *cropController = [[TOCropViewController alloc] initWithImage:image];
            cropController.delegate = self;
            //隐藏比例选择按钮
            cropController.aspectRatioPickerButtonHidden = YES;
            //重置后缩小到当前设置的长宽比
            cropController.resetAspectRatioEnabled = NO;
            //截图的展示样式
            cropController.aspectRatioPreset = TOCropViewControllerAspectRatioPresetSquare;
            //是否可以手动拖动
            cropController.cropView.cropBoxResizeEnabled = NO;
            [self presentViewController:cropController animated:NO completion:nil];
        }
        ALAuthorizationStatus author = [ALAssetsLibrary authorizationStatus];
        if (author == ALAuthorizationStatusRestricted || author == ALAuthorizationStatusDenied){
            //无权限
            return ;
        }
       UIImageWriteToSavedPhotosAlbum(image, self, nil, NULL);
       self.bottomImageView.image = image;
    }];
}

2.自定义截图功能
通过使用第三方截图框架(TOCropViewController)，实现自定义截图。
框架地址：TOCropViewController

 TOCropViewController *cropController = [[TOCropViewController alloc] initWithImage:image];
            cropController.delegate = self;
            //截图的展示样式
            cropController.aspectRatioPreset = TOCropViewControllerAspectRatioPresetSquare;
            //隐藏比例选择按钮
            cropController.aspectRatioPickerButtonHidden = YES;
            cropController.aspectRatioLockEnabled = YES;
            //重置后缩小到当前设置的长宽比
            cropController.resetAspectRatioEnabled = NO;
            
            //是否可以手动拖动
            cropController.cropView.cropBoxResizeEnabled = NO;
            
            [self presentViewController:cropController animated:NO completion:nil];

# pragma mark -TOCropViewControllerDelegate 图片裁剪
- (void)cropViewController:(TOCropViewController *)cropViewController didCropToImage:(UIImage *)image withRect:(CGRect)cropRect angle:(NSInteger)angle{

    UIImageWriteToSavedPhotosAlbum(image, self, nil, NULL);
    [self dismissViewControllerAnimated:NO completion:nil];
    [self dismissViewControllerAnimated:YES completion:nil];

}

3.聚焦功能、镜头切换功能、闪光灯功能以及镜头缩放功能
这些功能在DEMO中都做了详细的注释，就不在这里展开了，详见DEMO。

四、下一步将要完善的功能

DEMO会在GitHub不断更新,如果你有需要可以关注一下:
https://github.com/IMCCP
下一步将要完善的功能:
1.图片浏览器功能；
2.图片的美化以及滤镜功能；

感谢您的阅读，期待您的 Star，如果在使用中您有任何问题，可以在 github issue,我会尽自己能力给您答复 。