最近在做一個(gè)自定義相機(jī)的Demo， Demo的需求是相機(jī)對(duì)著某一處，當(dāng)自動(dòng)對(duì)焦成功后，然后拍攝圖片。
- (void)initAVCaptureSession{
self.session = [[AVCaptureSession alloc] init];
NSError *error;
self.device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
[self.device addObserver:self
forKeyPath:@"adjustingFocus"
options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld
context:nil];
//更改這個(gè)設(shè)置的時(shí)候必須先鎖定設(shè)備，修改完后再解鎖，否則崩潰
[self.device lockForConfiguration:nil];
//設(shè)置閃光燈為自動(dòng)
// [device setFlashMode:AVCaptureFlashModeOff];//AVCaptureFlashModeAuto
[self.device unlockForConfiguration];
self.videoInput = [[AVCaptureDeviceInput alloc] initWithDevice:self.device error:&error];
if (error) {
NSLog(@"%@",error);
}
self.stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
//輸出設(shè)置。AVVideoCodecJPEG 輸出jpeg格式圖片
NSDictionary * outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey, nil];
[self.stillImageOutput setOutputSettings:outputSettings];
if ([self.session canAddInput:self.videoInput]) {
[self.session addInput:self.videoInput];
}
if ([self.session canAddOutput:self.stillImageOutput]) {
[self.session addOutput:self.stillImageOutput];
}
self.session.sessionPreset = AVCaptureSessionPresetHigh;
//初始化預(yù)覽圖層
WEAKSELF
self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
[self.previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
weakSelf.previewLayer.frame = CGRectMake(0, 0,kScreenWidth, kScreenHeight);
dispatch_async(dispatch_get_main_queue(), ^{
weakSelf.cameraView.layer.masksToBounds = YES;
[weakSelf.cameraView.layer addSublayer:self.previewLayer];
});
});
}
自動(dòng)對(duì)焦的功能使用的是KVO實(shí)現(xiàn)的， 在上面的方法中添加了一個(gè)KVO：
[self.device addObserver:self
forKeyPath:@"adjustingFocus"
options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld
context:nil];
下面是自動(dòng)對(duì)焦KVO的方法：
-(void)observeValueForKeyPath:(NSString*)keyPath ofObject:(id)object change:(NSDictionary*)change context:(void*)context {
if([keyPath isEqualToString:@"adjustingFocus"]){
BOOL adjustingFocus =[[change objectForKey:NSKeyValueChangeNewKey] isEqualToNumber:[NSNumber numberWithInt:1]];
if (adjustingFocus == 0) {
[timer setFireDate:[NSDate distantFuture]];//停止
[self.device removeObserver:self forKeyPath:@"adjustingFocus"];
AVCaptureConnection *stillImageConnection = [self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo];
UIDeviceOrientation curDeviceOrientation = [[UIDevice currentDevice] orientation];
AVCaptureVideoOrientation avcaptureOrientation = [self avOrientationForDeviceOrientation:curDeviceOrientation];
[stillImageConnection setVideoOrientation:avcaptureOrientation];
[stillImageConnection setVideoScaleAndCropFactor:self.effectiveScale];
WEAKSELF
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:stillImageConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
if (!error) {
if (imageDataSampleBuffer == NULL) {
//沒有圖片
GPLog(@"當(dāng)前拍攝的圖片沒有數(shù)據(jù)！");
}
NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
ALAuthorizationStatus author = [ALAssetsLibrary authorizationStatus];
if (author == ALAuthorizationStatusRestricted || author == ALAuthorizationStatusDenied){
//無(wú)權(quán)限
[weakSelf showHUDText:@"沒有權(quán)限!"];
return;
}
UIImage *key_image = [UIImage imageWithData:jpegData];
if (!weakSelf.isPacket) {
weakSelf.cameraImg.hidden = NO;
weakSelf.cameraImg.image = [UIImage scaleImage:key_image WithSize:CGSizeMake(480, 480)];
weakSelf.cameraObj = key_image;
weakSelf.packetCannelBtn.hidden = NO;
weakSelf.packetHereBtn.hidden = NO;
} else {
NSURL *key_file = [NSURL URLWithString:weakSelf.storeModel.key_file_url];
[[SDWebImageManager sharedManager] loadImageWithURL:key_file options:0 progress:nil completed:^(UIImage * _Nullable image, NSData * _Nullable data, NSError * _Nullable error, SDImageCacheType cacheType, BOOL finished, NSURL * _Nullable imageURL) {
double key_image_double = [GetSimilarity getSimilarityValueWithImgA:image ImgB:key_image];
if (key_image_double >= 0.75) {
[weakSelf performSegueWithIdentifier:@"PacketDetailVC" sender:weakSelf.storeModel];
} else {
[self.device addObserver:self forKeyPath:@"adjustingFocus" options:NSKeyValueObservingOptionNew context:nil];
}
}];
}
}
});
}];
}
}
}
首先來(lái)說(shuō)說(shuō)Demo的需求， 其實(shí)需求也就是做一個(gè)類似支付寶AR紅包的APP，新版本的支付寶現(xiàn)在查看不了這個(gè)功能了。需求是這樣的， 首先相機(jī)使用自動(dòng)對(duì)焦拍攝一張圖片，然后埋下紅包或者圖片或者視頻， 然后上傳服務(wù)器。 附近的人查看到當(dāng)前位置有藏得紅包， 圖片或者視頻的時(shí)候， 可以通過(guò)支付寶相機(jī)的自動(dòng)對(duì)焦來(lái)獲取一張圖片和之前上傳服務(wù)器的圖片進(jìn)行對(duì)比，如果圖片匹配相同的， 就會(huì)打開紅包， 圖片或者視頻， 整個(gè)Demo的功能就是這樣的。
但是呢， 在iPhone 5s(我自己的手機(jī))， 上面使用這份代碼測(cè)試沒有一點(diǎn)問題， 但是使用iPhone7測(cè)試這份代碼的時(shí)候， 發(fā)現(xiàn)根本就不能。在iPhone 7上面， 第一次相機(jī)會(huì)很快的會(huì)自動(dòng)對(duì)焦成功， 然后自動(dòng)拍攝一張圖片， 但是這張圖片很模糊或者就是一張純黑的圖片，所以需要重新拍攝一張圖片。在自動(dòng)對(duì)焦成功后的代碼中， 我有使用：
[self.device removeObserver:self forKeyPath:@"adjustingFocus"];
下面的方法是點(diǎn)擊重新拍攝的方法，里面有重新添加自動(dòng)對(duì)焦的KVO：
- (IBAction)actionForPacketCannel:(id)sender {
[self addTimer];
self.cameraImg.hidden = YES;
self.packetHereBtn.hidden = YES;
self.packetCannelBtn.hidden = YES;
[self.device addObserver:self
forKeyPath:@"adjustingFocus"
options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld
context:nil];
}
但是現(xiàn)在的問題是：在iPhone7上面， 進(jìn)入到VC后，沒有多久， 他就自動(dòng)對(duì)焦成功，然后會(huì)拍攝圖片，但是這個(gè)圖片和iPhone5s上面對(duì)比，相差太遠(yuǎn)了，簡(jiǎn)直就不像是對(duì)焦成功后的，有時(shí)候既然是一張全黑的圖片。既然不是我想要的圖片， 我就按重新選擇圖片，然后重新添加KVO，然相機(jī)又自動(dòng)對(duì)焦，可是這個(gè)時(shí)候，怎么對(duì)焦都不成功！除非我把相機(jī)對(duì)著地板，或者相機(jī)要靠近物件只有幾厘米進(jìn)行對(duì)焦才會(huì)成功， 這個(gè)時(shí)候的圖片拍出來(lái)也是很模糊的。Why? 這是為什么啊 ？怎么感覺iPhone5s 和 iPhone 7 上面的不是一樣的效果，難道是iPhone 7 的手機(jī)相機(jī)又不同之處 ？求大神指點(diǎn)一二，謝謝！
