swift - 从 url 异步加载 anchor 不起作用

Question

使用 LoadAnchorAsync(contentsOf: URL) 加载 anchor 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")
}

但这每次都会因错误而崩溃:

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 block 中，它不会崩溃，但 reveiceCompletion 或 recieveValue 都不会被调用

Answer 1

你必须在 member 的某个地方存储 subscriber

// 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")
}