AVfoundation中焦距的设置(slider实现拉近拉远镜头)

首先设置一个slider

UISlider focusSlider = [[UISlideralloc]initWithFrame:CGRectMake(60,_bottomView.frame.origin.y-60,200,20)];

    [focusSlideraddTarget:selfaction:@selector(AdjustFocusAction:)forControlEvents:UIControlEventValueChanged];

    [focusSlidersetThumbImage:[UIImageimageNamed:@"camera_view_slider_take_gray.png"]forState:UIControlStateNormal];

    [focusSlidersetMinimumTrackImage:[UIImageimageNamed:@"camera_view_sliderbar_gray.png"]forState:UIControlStateNormal];

    [focusSlidersetMaximumTrackImage:[UIImageimageNamed:@"camera_view_sliderbar_gray.png"]forState:UIControlStateNormal];

    [focusSlidersetBackgroundColor:[UIColorclearColor]];

    [focusSlidersetMaximumValue:1];

    [focusSlidersetMinimumValue:0];

    [focusSlider
setValue:0.0];

    [self.viewaddSubview:focusSlider];
以下做一下有关相机的设置（只写出来了其中一部分，并非全部）

preview = [AVCaptureVideoPreviewLayerlayerWithSession:self.session];

    self.preview.frame =CGRectMake(0,0,
self.cameraView.frame.size.width,self.cameraView.frame.size.height);

    [self.previewsetPosition:CGPointMake(CGRectGetMidX(self.cameraView.bounds),CGRectGetMidY(self.cameraView.bounds))];

   

    self.preview.videoGravity =AVLayerVideoGravityResize;

    [self.cameraView.layeraddSublayer:self.preview];

captureOutput
= (AVCaptureStillImageOutput*)[self.session.outputsobjectAtIndex:0];

focusConnection =[captureOutput connectionWithMediaType:AVMediaTypeVideo]; 
  

                                                          
调节焦距

-(void)AdjustFocusAction:(id)sender
{

    [UIViewanimateWithDuration:0.025animations:^{

        [self.previewsetAffineTransform:CGAffineTransformMakeScale([(UISlider
*)sendervalue]+1, [(UISlider *)sendervalue]+1)];

        focusConnection.videoScaleAndCropFactor = [(UISlider *)sendervalue]+1;
    }];

}