从URL异步加载锚点无法工作

Question

使用 LoadAnchorAsync(contentsOf: URL) 加载锚点无法正常工作。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")
}

但是每次都崩溃并显示以下错误：

线程27：EXC_BREAKPOINT（code=1，subcode=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，但是既不调用reveiceCompletion也不调用recieveValue。

- Magnus T

Answer 1

你需要将订阅者存储在成员变量中

// 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")
}

- Asperi

Answer 2

试试这个

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

- deepak

---

Entity.load(contentsOf: url) 不返回 LoadRequest，因为它不是异步的。 - Magnus T