如何通过TabBarViewController的按钮控制UIView脉冲动画的启停

存在的问题 #

• 按钮点击事件未正确绑定：middleButton初始化闭包执行时实例尚未完成创建，此时绑定target指向错误，同时addTarget行存在缺失右括号的语法错误，导致点击按钮无法触发响应方法
• object属性未赋值：声明的MainViewObject!类型属性未绑定实际实例，值为nil，调用动画方法无任何效果
• 动画配置缺失必要参数：CAAnimation默认动画结束后自动移除，未设置持久化参数会导致动画无法持续运行
• 停止动画逻辑冗余：移除图层动画不需要包裹UIView动画块

修复步骤 #

1. 修复按钮初始化与事件绑定 #

将addTarget逻辑移到viewDidLoad中执行，补全语法错误，同时在合适位置给object属性赋值：

class TabbarViewController: UITabBarController {
   var object: MainViewObject!

    let middleButton: UIButton = {
        let btn = UIButton(frame: CGRect(x: (UIScreen.main.bounds.width / 2) - 32, y: -8, width: 65, height: 65))
        btn.setImage(UIImage(named: "play"), for: .normal)
        btn.layer.shadowColor = UIColor.black.cgColor
        btn.layer.shadowOpacity = 0.1
        btn.layer.shadowOffset = CGSize(width: 4, height: 4)
        btn.backgroundColor = Colors.mainColor
        btn.layer.cornerRadius = 32
        btn.tintColor = .clear
        return btn
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // 实例初始化完成后再绑定点击事件
        middleButton.addTarget(self, action:#selector(menuButtonAction), for: .touchUpInside)
        // 绑定MainViewController中的MainViewObject实例，此处示例根据你实际层级调整
        if let mainVC = viewControllers?.first as? MainViewController {
            // 替换为你MainViewController中持有MainViewObject的属性名
            self.object = mainVC.mainViewObject
        }
    }

    // 原有menuButtonAction等逻辑保持不变
}

2. 修复动画逻辑 #

补全动画持久化参数，添加空值判断避免崩溃，简化停止逻辑：

extension TabbarViewController { 
    func pulseAnimationStart() {
        guard let object = object else { return }
        // 先移除旧动画避免重复添加
        object.centerContainerView.layer.removeAnimation(forKey: "pulse")
        
        let fadingAnimation = CABasicAnimation(keyPath: "opacity")
        fadingAnimation.fromValue = 1
        fadingAnimation.toValue = 0.6 // 可按需调整透明度下限
        fadingAnimation.isRemovedOnCompletion = false

        let expandingAnimation = CABasicAnimation(keyPath: "transform.scale")
        expandingAnimation.fromValue = 1
        expandingAnimation.toValue = 1.1
        expandingAnimation.isRemovedOnCompletion = false

        let animationGroup = CAAnimationGroup()
        animationGroup.animations = [expandingAnimation, fadingAnimation]
        animationGroup.duration = 1.5
        animationGroup.repeatCount = .infinity
        animationGroup.isRemovedOnCompletion = false
        animationGroup.fillMode = .forwards
        
        object.centerContainerView.layer.add(animationGroup, forKey: "pulse")
    }

    func pulseAnimationStop() {
        guard let object = object else { return }
        object.centerContainerView.layer.removeAnimation(forKey: "pulse")
    }
}

内容的提问来源于stack exchange，提问作者zero_m