@Anil 的回答是一个很好的开始，但它对我不起作用。我希望能够让用户继续能够选择一个焦点，而不是只选择一次（这是他的解决方案所做的）。感谢@Anil 为我指明了正确的方向。
我的解决方案存在一些差异。
- 我希望能够重用焦点方块和动画，而不仅仅是一次。
- 我希望动画在完成后消失（这是我无法得到@Anil 的解决方案的事情。
- 我没有使用
initWithFrame:，而是实现了自己的initWithTouchPoint:.
- 我有一种专门为焦点动作设置动画的方法。
- 我还有一种更新框架位置的方法。
- 框架的大小在 范围内
CameraFocusSquare，这意味着更容易根据需要查找和更新大小。
CameraFocusSquare.h
@import UIKit;
@interface CameraFocusSquare : UIView
- (instancetype)initWithTouchPoint:(CGPoint)touchPoint;
- (void)updatePoint:(CGPoint)touchPoint;
- (void)animateFocusingAction;
@end
CameraFocusSquare.m
#import "CameraFocusSquare.h"
@implementation CameraFocusSquare {
CABasicAnimation *_selectionBlink;
}
/**
This is the init method for the square. It sets the frame for the view and sets border parameters. It also creates the blink animation.
*/
- (instancetype)initWithTouchPoint:(CGPoint)touchPoint {
self = [self init];
if (self) {
[self updatePoint:touchPoint];
self.backgroundColor = [UIColor clearColor];
self.layer.borderWidth = 2.0f;
self.layer.borderColor = [UIColor orangeColor].CGColor;
// create the blink animation
_selectionBlink = [CABasicAnimation
animationWithKeyPath:@"borderColor"];
_selectionBlink.toValue = (id)[UIColor whiteColor].CGColor;
_selectionBlink.repeatCount = 3; // number of blinks
_selectionBlink.duration = 0.4; // this is duration per blink
_selectionBlink.delegate = self;
}
return self;
}
/**
Updates the location of the view based on the incoming touchPoint.
*/
- (void)updatePoint:(CGPoint)touchPoint {
CGFloat squareWidth = 50;
CGRect frame = CGRectMake(touchPoint.x - squareWidth/2, touchPoint.y - squareWidth/2, squareWidth, squareWidth);
self.frame = frame;
}
/**
This unhides the view and initiates the animation by adding it to the layer.
*/
- (void)animateFocusingAction {
// make the view visible
self.alpha = 1.0f;
self.hidden = NO;
// initiate the animation
[self.layer addAnimation:_selectionBlink forKey:@"selectionAnimation"];
}
/**
Hides the view after the animation stops. Since the animation is automatically removed, we don't need to do anything else here.
*/
- (void)animationDidStop:(CAAnimation *)animation finished:(BOOL)flag {
// hide the view
self.alpha = 0.0f;
self.hidden = YES;
}
@end
我在视图之上启动所有这些。这给了我更大的灵活性，并将我的 UI 代码与我的控制器代码分开（想想 MVC）。
预览视图.h
@import UIKit;
@interface PreviewView : UIView
- (IBAction)tapToFocus:(UITapGestureRecognizer *)gestureRecognizer;
@end
预览视图.m
#import "PreviewView.h"
#import "CameraFocusSquare.h"
@implementation PreviewView {
CameraFocusSquare *_focusSquare;
}
- (IBAction)tapToFocus:(UITapGestureRecognizer *)gestureRecognizer {
CGPoint touchPoint = [gestureRecognizer locationOfTouch:0 inView:self];
if (!_focusSquare) {
_focusSquare = [[CameraFocusSquare alloc] initWithTouchPoint:touchPoint];
[self addSubview:_focusSquare];
[_focusSquare setNeedsDisplay];
}
else {
[_focusSquare updatePoint:touchPoint];
}
[_focusSquare animateFocusingAction];
}
@end
最后，在我的UIViewController子类中，我UITapGestureRecognizer创建并附加到视图。我还在这里实现了我的点击聚焦代码。
CameraViewController.m
- (void)viewDidLoad {
// do other initialization stuff here
// create the tap-to-focus gesture
UITapGestureRecognizer *tapToFocusRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapToFocus:)];
tapToFocusRecognizer.numberOfTapsRequired = 1;
tapToFocusRecognizer.numberOfTouchesRequired = 1;
[self.previewView addGestureRecognizer:tapToFocusRecognizer];
}
- (IBAction)tapToFocus:(UITapGestureRecognizer *)tapGestureRecognizer {
if (!_captureDevice) {
return;
}
if (![_captureDevice isFocusPointOfInterestSupported]) {
return;
}
if (![_captureDevice isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
return;
}
[self.previewView tapToFocus:tapGestureRecognizer];
NSError *error;
[_captureDevice lockForConfiguration:&error];
if (error) {
NSLog(@"Error trying to lock configuration of camera. %@", [error localizedDescription]);
return;
}
CGPoint touchPoint = [tapGestureRecognizer locationOfTouch:0 inView:self.cameraView];
// range of touch point is from (0,0) to (1,1)
CGFloat touchX = touchPoint.x / self.previewView.frame.size.width;
CGFloat touchY = touchPoint.y / self.previewView.frame.size.height;
_captureDevice.focusMode = AVCaptureFocusModeAutoFocus;
if ([_captureDevice isExposureModeSupported:AVCaptureExposureModeAutoExpose]) {
_captureDevice.exposureMode = AVCaptureExposureModeAutoExpose;
}
_captureDevice.focusPointOfInterest = CGPointMake(touchX, touchY);
if ([_captureDevice isExposurePointOfInterestSupported]) {
_captureDevice.exposurePointOfInterest = CGPointMake(touchX, touchY);
}
[_captureDevice unlockForConfiguration];
}
希望这对人们有所帮助，以便他们可以转向更重要的代码！