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：
2016-03-30 上午9.51.09.png
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?！ ‘斎灰部梢栽谇昂笾脭z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。
