使用 Metal 进行高效处理的 iOS UIKit 动画库。
它提供了一个优雅的 Swift API，用于动画您喜欢的任何属性。
保存 CPU 时间，用于处理事件而不是计算动画步骤。
注意：此版本目前为 BETA，请谨慎使用。
view.animate {
$0.alpha.target = 0.5
$0.center.target = CGPoint(x:100,y:200)
}.delay(2.0).animate {
$0.center.target = CGPoint(x:50,y:50)
$0.center.onChange = { newCenter in
print(newCenter)
}
$0.backgroundColor.target = UIColor.black
}.then {
print("Animation completed")
}弹簧动画最适合用于交互元素。无法指定动画的持续时间。相反，您指定弹簧的刚度阻尼。这就像在动画对象和目标之间连接一个弹簧。对象将遵循类似于平滑速度曲线的物理学。即使您更改动画目标，对象也会保持其速度，并按照自然曲线追踪新的目标。
您可以调整以下值来调整弹簧属性
调整这些值的方法如下
view.animate {
# this tells the animator to use spring animation with stiffness of 200, damping of 25, and default threshold
$0.type = .Spring(stiffness: 200, damping: 25, threshold: nil)
$0.center.target = CGPoint(x:100,y:200) // this animation is affected by the spring animation
$0.bounds.target = CGRect(x:0,y:0,width:100,height:100) // this is also affected
}.animate{
$0.backgroundColor.target = UIColor.black // this is not affected(still uses default stiffness, etc..)
}.Spring(stiffness: 200, damping: 10, threshold: 0.001)这是基本动画，允许您指定持续时间和曲线。当时间持续到时间达到时，对象将位于目标位置。
view.animate {
# this tells the animator to use tween animation with a bounce curve
$0.type = .Tween(duration: 2.0, curve: .bounce)
$0.center.target = CGPoint(x:100,y:200) // this animation is affected by the tween animation
$0.bounds.target = CGRect(x:0,y:0,width:100,height:100) // this is also affected
}.animate{
$0.backgroundColor.target = UIColor.black // this is not affected (still uses spring animation)
}默认情况下，所有属性（例如，以下示例中的 alpha、center、backgroundColor）都同时动画化。
view.animate {
$0.alpha.target = 0.5
$0.center.target = CGPoint(x:100,y:200)
}.animate {
$0.backgroundColor.target = UIColor.black
}使用 .then 或 .delay(time) 将动画分离成顺序组。
例如以下示例中，首先动画化 alpha 和 center。然后是 backgroundColor。然后2.0秒后，动画化 bounds。
view.animate {
$0.alpha.target = 0.5
$0.center.target = CGPoint(x:100,y:200)
}.then.animate {
$0.backgroundColor.target = UIColor.black
}.delay(2.0).animate {
$0.bounds.target = CGRect(x:0,y:0,width:100,height:100)
}view.delay(2).animate {
// this animation is trigger after 2 seconds
$0.alpha.target = 0.5
}.delay(2).animate {
// this animation is trigger after 4 seconds
$0.backgroundColor.target = UIColor.black
}使用 .then{ } 为动画完成注册回调
view.animate {
$0.alpha.target = 0.5
$0.center.target = CGPoint(x:100,y:200)
}.then {
print("First batch done!")
}.animate {
$0.backgroundColor.target = UIColor.black
}.then {
print("Second batch done!")
}
view.animate{
$0.center.target = CGPoint(x:200, y:200)
$0.center.onChange = { newCenter in
print(newCenter)
}
$0.center.onVelocityChange = { velocity in
print("velocity:\(velocity)")
}
}view.animate{
$0.custom(key: "myCustomProperty",
getter: { return view.myCustomProperty.toVec4 },
setter: { nv in view.myCustomProperty = CGFloat.fromVec4(nv) },
target: 100.toVec4 )
}class GPUAnimator{
// spring animation
func animate(_ item:T,
key:String,
getter:@escaping () -> float4,
setter:@escaping (inout float4) -> Void,
target:float4,
stiffness:Float = 200,
damping:Float = 10,
threshold:Float = 0.01,
completion:((Bool) -> Void)? = nil)
// tween animation
func animate(_ item:T,
key:String,
getter:@escaping () -> float4,
setter:@escaping (float4) -> Void,
target:float4,
duration:Float,
curve:Curve = .ease,
completion:((Bool) -> Void)? = nil)
// getting the velocity for a current running animation
func velocityFor(_ item:T, key:String)
}
// Example
class Foo{
var a:CGFloat = 0
}
var f = Foo()
// Animate f.a to 5, and print out it's velocity whenever the value changes
GPUAnimator.sharedInstance.animate(f,
key:"a",
getter:{ return f.a.toVec4 },
setter:{
f.a = CGFloat.fromVec4($0)
print(GPUAnimator.sharedInstance.velocityFor(f, key:"a"))
},
target:5.0.toVec4)