ios - 变换标签字体大小

Question

我有两个快捷方式。 它们每个都有初始属性，例如字体大小和不透明度。 动画之前，值为

labelOne.font = labelOne.font.withSize(109)
labelOne.alpha = 1.0

labelTwo.font = labelTwo.font.withSize(40)
labelTwo.alpha = 0.7

动画之后，它们应该具有以下属性:

labelOne.font = labelOne.font.withSize(40)
labelOne.alpha = 0.7

labelTwo.font = labelTwo.font.withSize(109)
labelTwo.alpha = 1.0

对于转换，我使用CGAffineTransform() 示例:

labelOne.transform = CGAffineTransform(scaleX: //some value? , y: //someValue?)

但是我是编程新手，不太明白它是如何工作的。告诉我如何编写这个调整字体大小的动画？

Answer 1

要在两个标签上实现动画，如您所愿，通过控制字体大小和 Alpha，您可以这样实现:

// Before animation
labelOne.font = labelOne.font.withSize(109)
labelOne.alpha = 1.0

labelTwo.font = labelTwo.font.withSize(40)
labelTwo.alpha = 0.7
UIView.animate(withDuration: 1, animations: {
    // This will be values set during the animation of 1 second
    self.labelOne.font = labelOne.font.withSize(40)
    self.labelOne.alpha = 0.7

    self.labelTwo.font = labelTwo.font.withSize(109)
    self.labelTwo.alpha = 1.0
})

同时，CGAffineTransform(scaleX:, y:) 允许您缩放 View 的 X,Y 坐标值(例如 labelOne)，但要通过动画实现这一点，您必须将在动画 block 内:

// normal state
labelOne.transform = CGAffineTransform(scaleX: 1, y: 1)
labelTwo.transform = CGAffineTransform(scaleX: 0.7, y: 0.7)
UIView.animate(withDuration: 1, animations: {
    // State reached through the animation
    labelOne.transform = CGAffineTransform(scaleX: 0.7, y: 0.7)
    labelTwo.transform = CGAffineTransform(scaleX: 1, y: 1)
})

要实现更平滑的过渡:

UIView.transition(with: labelOne, duration: 0.25, options: .transitionCrossDissolve, animations: {
    self.labelOne.font = UIFont.systemFont(ofSize: 40)
}) { _ in }