ios - iOS Swift 中的 CALayer 或 UIView？

Question

任何人都可以向我指出一个教程或示例代码(或两者!)来解释为 iOS 添加 View 和图层的正确方法。

理想情况下是 Swift，而不是 Obj C。

我有自己添加 SKNode 时有效的代码，没问题，但如果我添加渐变层 - 我希望它是背景中的天空，渐变会覆盖其他所有内容。

我尝试了各种形式的在上面的索引处添加子层等，但似乎没有任何效果。我想这就是我对CALayer和UIView的基本理解。我找不到好的教程:(

任何帮助表示赞赏。 干杯 亚当。

这是一个示例。
View 填充了渐变，这很棒，但是按钮似乎隐藏在下面，尽管试图将其强制置于背景层之上。

import QuartzCore
class NightScene: SKScene, SKPhysicsContactDelegate {

let playButton = SKSpriteNode(imageNamed: "play")


let gradient = CAGradientLayer()
    gradient.frame = view.bounds
    let colorTop = UIColor(red: 0.0, green: 0.0, blue: 0.100, alpha: 1.0).CGColor
    let colorMid = UIColor(red: 0.0, green: 0.0, blue: 0.450, alpha: 1.0).CGColor
    let colorBottom = UIColor(red: 0.0, green: 0.0, blue: 0.260, alpha: 1.0).CGColor
    let arrayColors: Array <AnyObject> = [colorTop, colorMid, colorBottom]
    gradient.colors = arrayColors
    gradient.locations = [ 0.0, 0.4, 1.0]
    self.view.layer.insertSublayer(gradient, atIndex:0)


    let sceneLayer = CALayer()
    sceneLayer.frame = view.bounds
    self.view.layer.insertSublayer(sceneLayer, above: gradient)

    self.playButton.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidX(self.frame)*2.5)
    self.addChild(playButton)

}

Answer 1

即使这个问题已经存在一年多了，我也会在自己无数个小时的搜索后提供答案。我发现了许多类似的问题，但没有/模糊的答复。

我发现节点不像渐变那样有层支持。这会导致渐变占据整个 UI View 。即使设置了 zLocation，节点也不可见。这适用于基于 SpriteKit 的项目。

我偶然发现了一个可以用来创建渐变背景的库。该库基本上将渐变转换为 SKSpriteNode。 渐变 -> 纹理 -> 节点

https://www.github.com/braindrizzlestudio/BDGradientNode

来自开发者

We wrote BDGradientNode because gradients are a bit of a pain to set up on the fly in SpriteKit. UIViews are CALayer-backed and have access to CAGradientLayer, making them simple--fairly simple--to make. (Though sweep gradients can't be done.) SKNodes are NOT layer-backed. While you can jump through some hoops to make images, and so textures, from layers that can be assigned to an SKSpriteNode (which is what we first did when we just needed a simple gradient in SpriteKit) it's both cumbersome and inflexible.

简单的线性背景

将库添加到您的 Xcode 项目后，您可以使用以下内容创建线性渐变背景:

    let color1 = UIColor(red: 0/255, green: 118/255, blue: 162/255, alpha: 1.0)
    let color2 = UIColor(red: 0/255, green: 85/255, blue: 116/255, alpha: 1.0)
    let colors = [color1, color2]

    let blending : Float = 1.0

    let startPoint = CGPoint(x: 0.5, y: 1.0)
    let endPoint = CGPoint(x: 0.5, y: 0.0)

    let nodeSize = CGSize(width: self.frame.width, height: self.size.height)

    let texture = SKTexture(imageNamed: "dummypixel")

    let myGradientNode = BDGradientNode(linearGradientWithTexture: texture, colors: colors, locations: nil, startPoint: startPoint, endPoint: endPoint, blending: blending, keepTextureShape: false, size: nodeSize)

    myGradientNode.zPosition = 0
    myGradientNode.position = CGPointMake(self.size.width/2, self.size.height/2)