Swift优化UI动画淡入淡出

UIView.animate(withDuration: 0.5, animations: {
    view.alpha = 0 // 淡出
}) { _ in
    // 动画完成后的操作
}

UIView.animate(withDuration: 0.5, animations: {
    view.alpha = 1 // 淡入
}) { _ in
    // 动画完成后的操作
}

let fadeOutAnimation = CABasicAnimation(keyPath: "opacity")
fadeOutAnimation.fromValue = 1 // 淡入
fadeOutAnimation.toValue = 0 // 淡出
fadeOutAnimation.duration = 0.5

let fadeInAnimation = CABasicAnimation(keyPath: "opacity")
fadeInAnimation.fromValue = 0 // 淡出
fadeInAnimation.toValue = 1 // 淡入
fadeInAnimation.duration = 0.5

view.layer.add(fadeOutAnimation, forKey: "fadeOut")
view.layer.add(fadeInAnimation, forKey: "fadeIn")