小编Дми*_*мов的帖子

我禁用了 SIP，但目录 /usr/bin 无论如何都是写保护的。如何获得/usr/bin 的写权限？请不要建议切换到/usr/local/bin。

我一直在尝试为ARSession期间检测到的QR码绘制边界框。结果是： boundingbox 1 boundingbox 2

正在跟踪条形码，但是边框的几何形状错误。

如何获得正确的边界框坐标？

源代码是：

 public func session(_ session: ARSession, didUpdate frame: ARFrame) {

     // Only run one Vision request at a time
     if self.processing {
         return
     }

    self.processing = true

    let request = VNDetectBarcodesRequest { (request, error) in

        if let results = request.results, let result = results.first as? VNBarcodeObservation {

            DispatchQueue.main.async {

                let path = CGMutablePath()

                for result in results {
                    guard let barcode = result as? VNBarcodeObservation else { continue }
                    let topLeft = self.convert(point: …

刚刚发现函数storeCachedResponse（_ cachedResponse：CachedURLResponse，用于请求：URLRequest）是异步工作的。也就是说，执行后不会立即返回结果。我没有在官方文档中找到对此的描述。参见示例：

cache = URLCache(memoryCapacity: 0, diskCapacity: 100 * 1024 * 1024, diskPath: "myCache")
let config = URLSessionConfiguration.default
config.requestCachePolicy = .returnCacheDataElseLoad
config.urlCache = cache
let session = URLSession(configuration: config)
session.dataTask(with: request, completionHandler: {[unowned self]
    (data, response, error) in

    if let data = data, let response = response, ((response as HTTPURLResponse)?.statusCode ?? 500) < 300 {
        let cachedData = CachedURLResponse(response: response, data: data)                                            
        self.cache.storeCachedResponse(cachedData, for: request)
        let testCachedData = self.cache.cachedResponse(for: request)
    }
}

理论上，testCachedData必须包含缓存的响应。但实际上包含的内容是：

testCachedData?.response.url // Ok
testCachedData?.isEmpty // false
testCachedData?.data …