animation - SceneKit Swift3 编译器错误

Question

我正在尝试在 SceneKit 中运行动画“DAE”模型:

let url = Bundle.main.url(forResource: "art.scnassets/Player(walking)", withExtension: "dae")
    let sceneSource = SCNSceneSource(url: url!, options: [SCNSceneSource.LoadingOption.animationImportPolicy: SCNSceneSource.AnimationImportPolicy.playRepeatedly] )
    let animationIds: NSArray = sceneSource?.identifiersOfEntries(withClass: CAAnimation)

    for eachId in animationIds {
        let animation: CAAnimation = (sceneSource?.entryWithIdentifier(eachId as! String, withClass: CAAnimation.self))!
        animations.add(animation)
    }
    character?._walkAnimations = animations

但是编译器它抛出就行了:

让 animationIds: NSArray = sceneSource?.identifiersOfEntries(withClass: CAAnimation)

并写出错误:

无法转换类型“[String]？”的值到指定类型 'NSArray'

请帮我解决这个问题。

提前致谢。

Answer 1

为什么要转换 [String]?至NSArray然后将每个元素转换为 String再次，不需要它，只需使用 Swift native Array并用 if let 包装可选值或 guard let .

guard let animationIds = sceneSource?.identifiersOfEntries(withClass: CAAnimation) else {
    return
}
for eachId in animationIds {
    if let animation = sceneSource?.entryWithIdentifier(eachId, withClass: CAAnimation.self) {
        animations.add(animation)
    }
}
character?._walkAnimations = animations