小编Wil*_*jay的帖子

我正在使用Xcode 8.0 beta 4.

在以前的版本中,UIViewController具有设置状态栏样式的方法

public func preferredStatusBarStyle() -> UIStatusBarStyle

但是,我发现它在Swift 3中改为"Get ONLY varaiable".

public var preferredStatusBarStyle: UIStatusBarStyle { get } 

如何在我的UIViewController中提供使用的样式？

如何像"相机"那样实时进行人脸检测？

我注意到,AVCaptureStillImageOutput为10.0后弃用,因此我用 AVCapturePhotoOutput代替.但是,我发现我为面部检测保存的图像并不那么令人满意？有任何想法吗？

UPDATE

在尝试了@Shravya Boggarapu之后提到.目前,我AVCaptureMetadataOutput用来检测脸部没有CIFaceDetector.它按预期工作.然而,当我试图画出脸部的边界时,似乎错位了.任何的想法？

let metaDataOutput = AVCaptureMetadataOutput()

captureSession.sessionPreset = AVCaptureSessionPresetPhoto
    let backCamera = AVCaptureDevice.defaultDevice(withDeviceType: .builtInWideAngleCamera, mediaType: AVMediaTypeVideo, position: .back)
    do {
        let input = try AVCaptureDeviceInput(device: backCamera)

        if (captureSession.canAddInput(input)) {
            captureSession.addInput(input)

            // MetadataOutput instead
            if(captureSession.canAddOutput(metaDataOutput)) {
                captureSession.addOutput(metaDataOutput)

                metaDataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
                metaDataOutput.metadataObjectTypes = [AVMetadataObjectTypeFace]

                previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
                previewLayer?.frame = cameraView.bounds
                previewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill

                cameraView.layer.addSublayer(previewLayer!)
                captureSession.startRunning()
            }

        }

    } catch {
        print(error.localizedDescription)
    }

和

extension CameraViewController: AVCaptureMetadataOutputObjectsDelegate {
func captureOutput(_ captureOutput: …

我有新的反应.我正在按照安装节点的教程步骤进行操作.但是,当我跑步时npm start,错误会一直显示出来.

Failed to compile.

./src/index.js
Module build failed: Error: Failed to load plugin import: Cannot find module 'eslint-plugin-import'
Referenced from: 
at Array.forEach (native)
at Array.reduceRight (native)

另外,我试图安装'eslint-plugin-import',但是徒劳无功......

npm install eslint-plugin-import -g

npm WARN eslint-plugin-import@2.7.0 requires a peer of eslint@2.x - 4.x but none was installed.

+ eslint-plugin-import@2.7.0

系统信息

eslint --version
v4.2.0

npm -v
5.2.0

npm list -g | grep eslint
??? eslint@4.2.0
? ??? eslint-scope@3.7.1
??? eslint-plugin-import@2.7.0
? ??? eslint-import-resolver-node@0.3.1
? ??? eslint-module-utils@2.1.1
??? eslint-plugin-react@7.1.0

自动调整掩码是否适用于iPhoneX？

当Apple 去年推出Auto Layout的新功能时,一切正常,没有任何限制.

但是,当我在iPhoneX模拟器上尝试自动布局时,它不适用于安全区域.

(✓使用安全区域布局指南)

Auto Layout (without constraint)

With constraints

当我使用 storyboard segue 时，在屏幕上显示另一个视图控制器非常流畅。但是，当我不使用 storyboard 时，只需添加一行简单的代码 with navigationController?.pushViewController(UIViewController(), animated: true)，它的过渡有点滞后。

我还阅读了推送视图控制器 (iOS) 时的延迟。但即使我正在推送一个全新的视图控制器（里面没有额外的代码），转换仍然有点滞后，知道吗？

我怎么能ARNode指向一个ARAnchor？

我想art.scnassets/ship.scn在屏幕中央使用显示并指向我刚刚放置在场景中的对象.

/// ViewController Class
func placeObject() {
    let screenCentre : CGPoint = CGPoint(x: self.sceneView.bounds.midX, y: self.sceneView.bounds.midY)
    guard let hitTestResult = sceneView.hitTest(screenCentre, types: [.featurePoint]).first else { return }

    // Place an anchor for a virtual character.
    let anchor = ARAnchor(name: identifierString, transform: hitTestResult.worldTransform)
    sceneView.session.add(anchor: anchor)
    // add to item model
    ItemModel.shared.anchors.append((identifierString, anchor)

}

func showDirection(of object: ARAnchor) { // object: saved anchor

    if !Guide.shared.isExist {
        let startPoint = SCNVector3(0, 0 , -1)
        let targetPoint …

我已经使用MapKit实现了 Apple SwiftUI 教程的略微更改版本。

当我运行它时，我收到错误消息并调整我得到的相应视图的大小：

[SwiftUI] NSHostingView is being laid out reentrantly while rendering its SwiftUI content. This is not supported and the current layout pass will be skipped.

查看调用代码：

    MapView(coordinate: location?.coordinates)
        .frame(minHeight: 200)
        .overlay(
            GeometryReader{
                proxy in
                Button("Open in Maps") {
                    if (self.location?.coordinates != nil){
                        let destination = MKMapItem(placemark: MKPlacemark(coordinate: self.location!.coordinates))
                        destination.name = "the car"
                        destination.openInMaps()
                    }
                }
                .frame(width: proxy.size.width, height: proxy.size.height, alignment: .bottomTrailing)
                .offset(x: -10, y: -10)
            }
    )

地图视图结构：

import SwiftUI
import MapKit

/// a …

我遇到了与内存相关的问题，也就是说，每当我转到另一个视图然后回退（关闭）时，内存就会不断堆积。

我的第二个viewController中有以下代码。但是，它不会取消分配内存。

    override func viewWillDisappear() {
        super.viewWillDisappear()
        self.dismissController(self)
        self.removeFromParentViewController()
}

提前致谢。

我目前正在使用 CoreBluetooth 开发 BLE 设备。我可以通过找到我的设备CBCentralManagerDelegate并连接到我的设备。

当我想发现一个服务的特性时，我可以得到正确的uuid，但是特性的值是nil。有任何想法吗？

func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
    if error != nil {
        print("ERROR DISCOVERING CHARACTERISTICS: \(error?.localizedDescription)")
        return
    }
    if let characteristics = service.characteristics {

        for characteristic in characteristics {
            print("--------------------------------------------")
            print("Characteristic UUID: \(characteristic.uuid)")
            print("Characteristic isNotifying: \(characteristic.isNotifying)")
            print("Characteristic properties: \(characteristic.properties)")
            print("Characteristic descriptors: \(characteristic.descriptors)")
            print("Characteristic value: \(characteristic.value)")
        }
    }
}

-------------------------------------------------------------------
Characteristic UUID: FA01
Characteristic isNotifying: false
Characteristic properties: CBCharacteristicProperties(rawValue: 26)
Characteristic descriptors: nil
Characteristic value: nil

根据蓝牙 …

我想计算没有循环的SVM的损失。但我无法把它做好。需要一些启示。

          和          

def svm_loss_vectorized(W, X, y, reg):
    loss = 0.0
    scores = np.dot(X, W)
    correct_scores = scores[y]
    deltas = np.ones(scores.shape)
    margins = scores - correct_scores + deltas

    margins[margins < 0] = 0  # max -> Boolean array indexing
    margins[np.arange(scores.shape[0]), y] = 0  # Don't count j = yi
    loss = np.sum(margins)

    # Average
    num_train = X.shape[0]
    loss /= num_train

    # Regularization
    loss += 0.5 * reg * np.sum(W * W)
    return loss

它应该输出与以下函数相同的损失。

def svm_loss_naive(W, X, y, reg):
    num_classes = …