如何使用AVCaptureDevice保存图像

Question

I'm using Apple's GLCameraRipple example code in my project and I was wondering if there is a way to take a pic/video? Project can be found at https://developer.apple.com/library/ios/samplecode/GLCameraRipple/Introduction/Intro.html

Answer 1

First of all, ensure that you have included AssetLibrary framework, because we need that to access the photo library. Assuming that you have set up the capture AVCaptureSession, AVCaptureDevice, and AVCaptureStillImageOutput (stillImage) correctly, now you can create a button or simply call the below function to save an image.

-(void)captureMultipleTimes
{
AVCaptureConnection *connection = [stillImage connectionWithMediaType:AVMediaTypeVideo];

typedef void(^MyBufBlock)(CMSampleBufferRef, NSError*);

MyBufBlock h = ^(CMSampleBufferRef buf, NSError *err){
    NSData *data = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:buf];
    [self setToSaveImage:[UIImage imageWithData:data]];

    dispatch_async(dispatch_get_main_queue(), ^{
        if(saveLabel == NULL){
            [self setSaveLabel:[[UILabel alloc] initWithFrame:CGRectMake(0,self.view.bounds.size.height/2, self.view.bounds.size.width, 50)]];
            [saveLabel setText:@"Saving.."];
            [saveLabel setTextColor:[captureBt titleColorForState:UIControlStateNormal]];
            [self.view addSubview:saveLabel];
        } else
            saveLabel.hidden = NO;

        UIImageWriteToSavedPhotosAlbum(toSaveImage, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
    });
};
[stillImage captureStillImageAsynchronouslyFromConnection:connection completionHandler:h];
}

You also need to implement the image:didFinishSavingWithError:contextInfo: method as the completion function of saving image. One example is as follows:

-(void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
if(error != NULL){
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error!" message:@"Image could not be saved" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
    [alert show];
}
else{
    [saveLabel setHidden:YES];
}
}

The functions above will display "Saving.." label on the screen once you trigger the captureMultipleTimes function. It simply means that it is currently saving the video input as an image and store it into the photo lib. Once it has finished saving, the saving label will be hidden from the screen. Hope this helps!