AVFoundation 点击​​聚焦反馈矩形

我正在开发一个 iPhone 应用程序，我直接使用 AVFoundation 通过相机捕获视频。

我已经实现了一项功能来启用tap to focus为用户提供的功能。

- (void) focus:(CGPoint) aPoint;
{
#if HAS_AVFF
    Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
    if (captureDeviceClass != nil) {        
        AVCaptureDevice *device = [captureDeviceClass defaultDeviceWithMediaType:AVMediaTypeVideo];
        if([device isFocusPointOfInterestSupported] &&
           [device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
            CGRect screenRect = [[UIScreen mainScreen] bounds];
            double screenWidth = screenRect.size.width;
            double screenHeight = screenRect.size.height;
            double focus_x = aPoint.x/screenWidth;
            double focus_y = aPoint.y/screenHeight;
            if([device lockForConfiguration:nil]) {
                [device setFocusPointOfInterest:CGPointMake(focus_x,focus_y)];
                [device setFocusMode:AVCaptureFocusModeAutoFocus];
                if ([device isExposureModeSupported:AVCaptureExposureModeAutoExpose]){
                    [device setExposureMode:AVCaptureExposureModeAutoExpose];
                }
                [device unlockForConfiguration];
            }
        }
    }
#endif
}

到目前为止一切顺利，但我缺少像照片应用程序中那样的反馈矩形。有什么方法可以告诉 AVFoundation 框架显示此反馈矩形，还是我必须自己实现此功能？

这就是我所做的： 这个类创建当用户点击相机覆盖层时显示的正方形。

CameraFocusSquare.h

#import <UIKit/UIKit.h>
@interface CameraFocusSquare : UIView
@end


CameraFocusSquare.m

#import "CameraFocusSquare.h"
#import <QuartzCore/QuartzCore.h>

const float squareLength = 80.0f;
@implementation FBKCameraFocusSquare

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code

        [self setBackgroundColor:[UIColor clearColor]];
        [self.layer setBorderWidth:2.0];
        [self.layer setCornerRadius:4.0];
        [self.layer setBorderColor:[UIColor whiteColor].CGColor];

        CABasicAnimation* selectionAnimation = [CABasicAnimation
                                                animationWithKeyPath:@"borderColor"];
        selectionAnimation.toValue = (id)[UIColor blueColor].CGColor;
        selectionAnimation.repeatCount = 8;
        [self.layer addAnimation:selectionAnimation
                          forKey:@"selectionAnimation"];

    }
    return self;
}
@end

在您收到点按的视图中，执行以下操作：

- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchPoint = [touch locationInView:touch.view];
    [self focus:touchPoint];

    if (camFocus)
    {
        [camFocus removeFromSuperview];
    }
    if ([[touch view] isKindOfClass:[FBKVideoRecorderView class]])
    {
        camFocus = [[CameraFocusSquare alloc]initWithFrame:CGRectMake(touchPoint.x-40, touchPoint.y-40, 80, 80)];
        [camFocus setBackgroundColor:[UIColor clearColor]];
        [self addSubview:camFocus];
        [camFocus setNeedsDisplay];

        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:1.5];
        [camFocus setAlpha:0.0];
        [UIView commitAnimations];
    }
}

- (void) focus:(CGPoint) aPoint;
{
    Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
    if (captureDeviceClass != nil) {
        AVCaptureDevice *device = [captureDeviceClass defaultDeviceWithMediaType:AVMediaTypeVideo];
        if([device isFocusPointOfInterestSupported] &&
           [device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
            CGRect screenRect = [[UIScreen mainScreen] bounds];
            double screenWidth = screenRect.size.width;
            double screenHeight = screenRect.size.height;
            double focus_x = aPoint.x/screenWidth;
            double focus_y = aPoint.y/screenHeight;
            if([device lockForConfiguration:nil]) {
                [device setFocusPointOfInterest:CGPointMake(focus_x,focus_y)];
                [device setFocusMode:AVCaptureFocusModeAutoFocus];
                if ([device isExposureModeSupported:AVCaptureExposureModeAutoExpose]){
                    [device setExposureMode:AVCaptureExposureModeAutoExpose];
                }
                [device unlockForConfiguration];
            }
        }
    }
}