如何使用swift 3将按钮动画化为淡出，然后再淡入

import UIKit

let button = UIButton()
button.frame = CGRect(x: 100, y: 100, width: 100, height: 50)
button.backgroundColor = UIColor.red
self.view.addSubview(button)

func fadeOutAnimation() {
    UIView.animate(withDuration: 1.0, animations: {
        self.button.alpha = 0.0
    })
}

func fadeInAnimation() {
    UIView.animate(withDuration: 1.0, animations: {
        self.button.alpha = 1.0
    })
}

// 淡出动画
fadeOutAnimation()

// 延迟一段时间后执行淡入动画
DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
    self.fadeInAnimation()
}