swift - 从 url 异步加载锚点不起作用

Question

使用 LoadAnchorAsync(contentsOf: URL) 加载锚点不起作用。这是我的代码：

if let url = url {
    let loadRequest = Entity.loadAnchorAsync(contentsOf: url)
    _ = loadRequest.sink(receiveCompletion: { completion in
        // handle completion
    }, receiveValue: { anchor in
        self.arView.scene.addAnchor(anchor)
    })
} else {
        fatalError("no url")
}

但这每次都会崩溃并出现错误：

线程 27：EXC_BREAKPOINT（代码=1，子代码=0x1051e0dfc）

更新：如果我将整个代码块包装在 DispatchQueue.main.async 块中，它不会崩溃，但不会调用 reveiceCompletion 或 recieveValue

标签： swiftaugmented-realityarkitcombinerealitykit

Answer 1

您必须将订阅者存储在成员中的某个位置

// somewhere above
private var subscribers: Set<AnyCancellable>()

...
if let url = url {
    let loadRequest = Entity.loadAnchorAsync(contentsOf: url)
    loadRequest.sink(receiveCompletion: { completion in
        // handle completion
    }, receiveValue: { anchor in
        self.arView.scene.addAnchor(anchor)
    }).store(in: &self.subscribers) // << keep it alive
} else {
        fatalError("no url")
}