最近公司的項目中用到了相機，由于不用系統的相機，UI給的相機切圖，必須自定義才可以。就花時間簡單研究了一下相機的自定義。
相機屬于系統硬件，這就需要我們來手動調用iPhone的相機硬件，分為以下步驟：
1、首先聲明以下對象
#import <AVFoundation/AVFoundation.h>//捕獲設備，通常是前置攝像頭，后置攝像頭，麥克風（音頻輸入）@property (nonatomic, strong) AVCaptureDevice *device; //AVCaptureDeviceInput 代表輸入設備，他使用AVCaptureDevice 來初始化@property (nonatomic, strong) AVCaptureDeviceInput *input; //輸出圖片@property (nonatomic ,strong) AVCaptureStillImageOutput *imageOutput; //session：由他把輸入輸出結合在一起，并開始啟動捕獲設備（攝像頭）@property (nonatomic, strong) AVCaptureSession *session; //圖像預覽層，實時顯示捕獲的圖像@property (nonatomic ,strong) AVCaptureVideoPreviewLayer *previewLayer;
2、初始化各個對象
- (void)cameraDistrict{// AVCaptureDevicePositionBack 后置攝像頭// AVCaptureDevicePositionFront 前置攝像頭 self.device = [self cameraWithPosition:AVCaptureDevicePositionFront]; self.input = [[AVCaptureDeviceInput alloc] initWithDevice:self.device error:nil]; self.imageOutput = [[AVCaptureStillImageOutput alloc] init]; self.session = [[AVCaptureSession alloc] init]; // 拿到的圖像的大小可以自行設定 // AVCaptureSessionPreset320x240 // AVCaptureSessionPreset352x288 // AVCaptureSessionPreset640x480 // AVCaptureSessionPreset960x540 // AVCaptureSessionPreset1280x720 // AVCaptureSessionPreset1920x1080 // AVCaptureSessionPreset3840x2160 self.session.sessionPreset = AVCaptureSessionPreset640x480; //輸入輸出設備結合 if ([self.session canAddInput:self.input]) { [self.session addInput:self.input]; } if ([self.session canAddOutput:self.imageOutput]) { [self.session addOutput:self.imageOutput]; } //預覽層的生成 self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session]; self.previewLayer.frame = CGRectMake(0, 64, SCREEN_WIDTH, SCREEN_HEIGHT-64); self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill; [self.view.layer addSublayer:self.previewLayer]; //設備取景開始 [self.session startRunning]; if ([_device lockForConfiguration:nil]) { //自動閃光燈， if ([_device isFlashModeSupported:AVCaptureFlashModeAuto]) { [_device setFlashMode:AVCaptureFlashModeAuto]; } //自動白平衡,但是好像一直都進不去 if ([_device isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeAutoWhiteBalance]) { [_device setWhiteBalanceMode:AVCaptureWhiteBalanceModeAutoWhiteBalance]; } [_device unlockForConfiguration]; } }根據前后置位置拿到相應的攝像頭：
- (AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition)position{ NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; for ( AVCaptureDevice *device in devices ) if ( device.position == position ){ return device; } return nil;}3、拍照拿到相應圖片：
- (void)photoBtnDidClick{ AVCaptureConnection *conntion = [self.imageOutput connectionWithMediaType:AVMediaTypeVideo]; if (!conntion) { NSLog(@"拍照失敗!"); return; } [self.imageOutput captureStillImageAsynchronouslyFromConnection:conntion completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) { if (imageDataSampleBuffer == nil) { return ; } NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer]; self.image = [UIImage imageWithData:imageData]; [self.session stopRunning]; [self.view addSubview:self.cameraImageView];}4、保存照片到相冊：
#pragma - 保存至相冊- (void)saveImageToPhotoAlbum:(UIImage*)savedImage{ UIImageWriteToSavedPhotosAlbum(savedImage, self, @selector(image:didFinishSavingWithError:contextInfo:), NULL); }// 指定回調方法 - (void)image: (UIImage *) image didFinishSavingWithError: (NSError *) error contextInfo: (void *) contextInfo { NSString *msg = nil ; if(error != NULL){ msg = @"保存圖片失敗" ; }else{ msg = @"保存圖片成功" ; } UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"保存圖片結果提示" message:msg delegate:self cancelButtonTitle:@"確定" otherButtonTitles:nil]; [alert show];}5、前后置攝像頭的切換
- (void)changeCamera{ NSUInteger cameraCount = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count]; if (cameraCount > 1) { NSError *error; //給攝像頭的切換添加翻轉動畫 CATransition *animation = [CATransition animation]； animation.duration = .5f； animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; animation.type = @"oglFlip"; AVCaptureDevice *newCamera = nil; AVCaptureDeviceInput *newInput = nil; //拿到另外一個攝像頭位置 AVCaptureDevicePosition position = [[_input device] position]; if (position == AVCaptureDevicePositionFront){ newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack]; animation.subtype = kCATransitionFromLeft;//動畫翻轉方向 } else { newCamera = [self cameraWithPosition:AVCaptureDevicePositionFront]; animation.subtype = kCATransitionFromRight;//動畫翻轉方向 } //生成新的輸入 newInput = [AVCaptureDeviceInput deviceInputWithDevice:newCamera error:nil]; [self.previewLayer addAnimation:animation forKey:nil]; if (newInput != nil) { [self.session beginConfiguration]; [self.session removeInput:self.input]; if ([self.session canAddInput:newInput]) { [self.session addInput:newInput]; self.input = newInput; } else { [self.session addInput:self.input]; } [self.session commitConfiguration]; } else if (error) { NSLog(@"toggle carema failed, error = %@", error); } }}6、相機的其它參數設置
//AVCaptureFlashMode 閃光燈//AVCaptureFocusMode 對焦//AVCaptureExposureMode 曝光//AVCaptureWhiteBalanceMode 白平衡//閃光燈和白平衡可以在生成相機時候設置//曝光要根據對焦點的光線狀況而決定,所以和對焦一塊寫//point為點擊的位置- (void)focusAtPoint:(CGPoint)point{ CGSize size = self.view.bounds.size; CGPoint focusPoint = CGPointMake( point.y /size.height ,1-point.x/size.width ); NSError *error; if ([self.device lockForConfiguration:&error]) { //對焦模式和對焦點 if ([self.device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) { [self.device setFocusPointOfInterest:focusPoint]; [self.device setFocusMode:AVCaptureFocusModeAutoFocus]; } //曝光模式和曝光點 if ([self.device isExposureModeSupported:AVCaptureExposureModeAutoExpose ]) { [self.device setExposurePointOfInterest:focusPoint]; [self.device setExposureMode:AVCaptureExposureModeAutoExpose]; } [self.device unlockForConfiguration]; //設置對焦動畫 _focusView.center = point; _focusView.hidden = NO; [UIView animateWithDuration:0.3 animations:^{ _focusView.transform = CGAffineTransformMakeScale(1.25, 1.25); }completion:^(BOOL finished) { [UIView animateWithDuration:0.5 animations:^{ _focusView.transform = CGAffineTransformIdentity; } completion:^(BOOL finished) { _focusView.hidden = YES; }]; }]; } }7、遇到的一些坑和解決辦法
1) 前后置攝像頭的切換
前后值不能切換，各種嘗試找了半天沒找到有原因。后來發現我在設置圖片尺寸的時候設置為1080P [self.session canSetSessionPreset: AVCaptureSessionPreset1920x1080] ，前置攝像頭并不支持這么大的尺寸，所以就不能切換前置攝像頭。我驗證了下 前置攝像頭最高支持720P,720P以內可自由切換。
當然也可以在前后置攝像頭切換的時候，根據前后攝像頭來設置不同的尺寸，這里不在贅述。
2）焦點位置
CGPoint focusPoint = CGPointMake( point.y /size.height ,1-point.x/size.width );
setExposurePointOfInterest：focusPoint 函數后面Point取值范圍是取景框左上角（0，0）到取景框右下角（1，1）之間。官方是這么寫的：
The value of this property is a CGPoint that determines the receiver's focus point of interest, if it has one. A value of (0,0) indicates that the camera should focus on the top left corner of the image, while a value of (1,1) indicates that it should focus on the bottom right. The default value is (0.5,0.5).
我也試了按這個來但位置就是不對，只能按上面的寫法才可以。前面是點擊位置的y/PreviewLayer的高度，后面是1-點擊位置的x/PreviewLayer的寬度
3）對焦和曝光
我在設置對焦是 先設置了模式setFocusMode，后設置對焦位置，就會導致很奇怪的現象，對焦位置是你上次點擊的位置。所以一定要先設置位置，再設置對焦模式。
曝光同上
8、寫在最后
附上demo：photographDemo
常用到的基本就這么多，寫的并不完善，有什么不對的，歡迎大家批評指正，共同學習。
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。
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