动画背景颜色变化 - 并排答案

【问题标题】：Animating Background Color Change - Side to Side动画背景颜色变化 - 并排
【发布时间】：2016-04-29 17:28:13
【问题描述】：

假设我有一个水平长的矩形。它是蓝色的。我希望它是红色的。但是，我希望颜色变化从一侧开始并在另一侧结束。

我可以使用关键帧动画让整个视图逐渐从红色变为蓝色。有没有办法从左-右/右-左逐渐改变？？

UIView.animateKeyframesWithDuration(2.0 /*Total*/, delay: 0.0, options: UIViewKeyframeAnimationOptions.CalculationModeLinear, animations: {
    UIView.addKeyframeWithRelativeStartTime(0.0, relativeDuration: 1/1, animations:{
        self.view.backgroundColor = UIColor.redColor()    
        self.view.layoutIfNeeded()
    })
    },
     completion: { finished in
        if (!finished) { return }
})

【问题讨论】：

标签： ios swift uiviewanimation

【解决方案1】：

看看CAGradientLayer。您可以为其locations、colors 或endPoint 和startPoint 设置动画

这是一个快速的 sn-p，您可以将其粘贴到 Playground 中，看看它是如何工作的。在这种情况下，我正在为渐变颜色位置设置动画。

import UIKit
import XCPlayground

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true

let view = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 400))

let startLocations = [0, 0]
let endLocations = [1, 2]

let layer = CAGradientLayer()
layer.colors = [UIColor.redColor().CGColor, UIColor.blueColor().CGColor]
layer.frame = view.frame
layer.locations = startLocations
layer.startPoint = CGPoint(x: 0.0, y: 1.0)
layer.endPoint = CGPoint(x: 1.0, y: 1.0)
view.layer.addSublayer(layer)

let anim = CABasicAnimation(keyPath: "locations")
anim.fromValue = startLocations
anim.toValue = endLocations
anim.duration = 2.0
layer.addAnimation(anim, forKey: "loc")
layer.locations = endLocations

XCPlaygroundPage.currentPage.liveView = view

【讨论】：

【解决方案2】：

Swift 3 版本：

import UIKit
import PlaygroundSupport

PlaygroundPage.current.needsIndefiniteExecution = true


let view = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 400))

let startLocations = [0, 0]
let endLocations = [1, 2]

let layer = CAGradientLayer()
layer.colors = [UIColor.red.cgColor, UIColor.blue.cgColor]
layer.frame = view.frame
layer.locations = startLocations as [NSNumber]?
layer.startPoint = CGPoint(x: 0.0, y: 1.0)
layer.endPoint = CGPoint(x: 1.0, y: 1.0)
view.layer.addSublayer(layer)

let anim = CABasicAnimation(keyPath: "locations")
anim.fromValue = startLocations
anim.toValue = endLocations
anim.duration = 2.0
layer.add(anim, forKey: "loc")
layer.locations = endLocations as [NSNumber]?

PlaygroundPage.current.liveView = view

【讨论】：