小编Sal*_*500的帖子

回溯和递归有什么区别？这个程序如何运作？

void generate_all(int n)
 {
    if(n<1) printf("%s\n", ar);
    else{
            ar[n-1]='0';        //fix (n)th bit as '0'
            generate_all(n-1);  //generate all combinations for other n-1 positions.
            ar[n-1]='1';        //fix (n)th bit as '1'
            generate_all(n-1);  //generate all combinations for other n-1 positions.
    }

作为From Firebase JobDispatcher文档Firebase JobDispatcher

setTrigger(Trigger.executionWindow(0, 60))
// start between 0 and 60 seconds

但为什么我的服务运行两次

Firebase JobDispacther代码

    FirebaseJobDispatcher dispatcher = new FirebaseJobDispatcher(new GooglePlayDriver(this));
    Job job = dispatcher.newJobBuilder()
            .setTag("testing job")
            .setService(TestingJob.class)
            .setReplaceCurrent(true)
            .setRecurring(true)
            .setTrigger(Trigger.executionWindow(0,1))
            .setConstraints(Constraint.ON_ANY_NETWORK)
            .setLifetime(Lifetime.FOREVER)
            .build();

    dispatcher.mustSchedule(job);

测试类(工作服务)

public class TestingJob extends JobService {

    private static final String TAG = "TestingJob";
    private int i =0;
    @Override
    public boolean onStartJob(JobParameters job) {

        Log.d(TAG, "onStartJob Testing Job: "+new Date().toString());
        Log.d(TAG, "onStartJob: i = "+String.valueOf(i));
        i+=1;
        return false;
    }

    @Override
    public boolean onStopJob(JobParameters …

作为来自Android开发人员JobIntentService在Android O或更高版本上运行时,工作将作为作业通过分派JobScheduler.enqueue.在旧版本的平台上运行时,它将使用Context.startService.

在我的情况下,我正在学习JobIntentService,在我的情况下,我有一个计时器,每秒运行一次并显示当前的日期和时间,但当我的应用程序被销毁时,JobIntentService也被销毁,如何在销毁应用程序时运行它

JobIntentService

class OreoService : JobIntentService() {

    private val handler = Handler()

    companion object {
        private const val JOB_ID = 123

        fun enqueueWork(cxt: Context, intent: Intent){
            enqueueWork(cxt,OreoService::class.java,JOB_ID,intent)
        }
    }

    override fun onHandleWork(intent: Intent) {

        toast(intent.getStringExtra("val"))

        Timer().scheduleAtFixedRate(object : TimerTask() {
            override fun run() {
                println(Date().toString())
            }

        }, Date(),1000)

    }

    override fun onDestroy() {
        super.onDestroy()
        toast("Service Destroyed")
    }

   private fun toast(msg: String){

       handler.post({
           Toast.makeText(applicationContext,msg,Toast.LENGTH_LONG).show()
       })
   }
}

表现

<uses-permission android:name="android.permission.WAKE_LOCK"/> …

我有一个显示国家/地区图像、名称和电话代码的列表，我想知道选择了哪个国家/地区，就像UITableView中一样 didSelectRowAt indexPath

语言环境信息

struct LocaleInfo: Codable, Identifiable {
    let id = UUID()
    let name: String
    let dialCode: String
    let code: String

    var flag: UIImage? {
        return UIImage(named: "Countries.bundle/Images/\(code.uppercased())", in: Bundle.main, compatibleWith: nil)
    }

}

斯威夫特用户界面

List(filterLocaleInfo.filter({ $0.name.hasPrefix(search) })) { info in
            HStack(alignment: .center) {
                Image(uiImage: info.flag ?? UIImage())
                VStack(alignment: .leading) {
                    Text(info.name)
                        .font(.custom("Avenir-Medium", size: 17))

                    Text(info.dialCode)
                        .font(.custom("Avenir-Book", size: 15))
                }
            }
        }
        .onAppear { self.getLocaleData() }

我正在创建圆形填充动画,但我的圆圈填充为80%,50%不是一半,有什么方法可以纠正因为我很困惑

class FillCircleAnimatedView : UIView {

    private let shapeLayer = CAShapeLayer()

    override init(frame: CGRect) {
        super.init(frame: frame)

        setUpLayer()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    func setUpLayer() {

        shapeLayer.fillColor = UIColor.clear.cgColor
        shapeLayer.strokeColor = UIColor.black.cgColor
        shapeLayer.lineWidth = frame.width

        let startAngle = (-1 * CGFloat.pi) / 2
        let endAngle = 2 * CGFloat.pi


        shapeLayer.path = UIBezierPath(arcCenter: center, radius: frame.width / 2, startAngle: startAngle, endAngle: endAngle, clockwise: true).cgPath

        shapeLayer.strokeEnd = 0

        layer.addSublayer(shapeLayer)
    }

    func fillCircle(with progress: CGFloat) { …

我正在使用react-native-sensor从传感器获取原始数据。

setUpdateIntervalForType(SensorTypes.gyroscope, 100)

gyroscope.subscribe(({ x, y, z, timestamp }) => {
  let pitch = Math.atan2(-x, -z) * 180 / Math.PI;// In degrees
  let roll = Math.atan2(-y, -x) * 180 / Math.PI;// In degrees
  let yaw = Math.atan2(y, -z) * 180 / Math.PI;// In degrees
  
  this.setState({pitch: pitch, roll: roll, yaw: yaw})
})

我怎么知道设备被旋转了 360

我有 3 个单元格，第一个单元格有标签，第二个单元格有文本字段，最后一个单元格有按钮，通过使用它可以自动调整大小，但如何删除单元格之间的空间

if let flowlayout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
            flowlayout.estimatedItemSize = UICollectionViewFlowLayoutAutomaticSize
        }

或者如何在我的场景中使用这种方法

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    code
}

用户停止输入 0.3 秒后的更改应显示在标签中，但 subscribe onNext 未调用

override func viewDidLoad() {
    ...
    let disposeBag = DisposeBag()
    textfield.rx.text.orEmpty
        .debounce(.milliseconds(300), scheduler: MainScheduler.instance)
        .subscribe(onNext: { [unowned self] (text) in
            self.label.text = text
        }).disposed(by: disposebag)
    ...
}

使用Swift 5

pod 'RxSwift', '~> 5'
pod 'RxCocoa', '~> 5'