Question

如何创建一个while循环，每秒检查一次？

可能是这样的：

while (isConditionSatisfied){
// wait for 1 second and than check again
}

编辑：系统随机调用此函数bannerViewDidLoadAd。如果它在不适当的时间调用它（条件不满意 - 我的应用程序正在执行其他动画），我想推迟其实现（只是一个UIView动画），直到满足条件（我的应用程序已完成动画，现在实现应该被执行）。我以为我可以每秒钟检查一下这个状态，但正如你们所说的那样......这是一个坏主意。

Answer 1

像这样使用while循环实际上会创建一个无限循环。你应该使用Timer（）。

package com.lightelements.carddroid;

import android.content.Context;
import android.support.v4.app.FragmentManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.List;

/**
 * Created by User on 11/09/2015.
 */

public class CardsCustomAdapter extends ArrayAdapter<Card> {
private LayoutInflater mLayoutInflater;
private static FragmentManager sFragmentManager;

    public CardsCustomAdapter(Context context, FragmentManager fragmentManager){
    super(context, android.R.layout.simple_list_item_2);
    mLayoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    sFragmentManager = fragmentManager;
}

public CardsCustomAdapter(Context context){
    super(context, android.R.layout.simple_list_item_2);
    mLayoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    final View view;
    if (convertView == null) {
        view = mLayoutInflater.inflate(R.layout.custom_card, parent, false);
    } else {
        view = convertView;
    }

    final Card card = getItem(position);
    final int _id = card.getId();
    final String name = card.getCard_name();

    ((TextView) view.findViewById(R.id.card_name)).setText(name);

    return view;
}

public void setData(List<Card> cards){
    clear();
    if (cards != null) {
        for (Card card : cards) {
            add(card);
        }
    }
}
}

然后

timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(self.loop), userInfo: nil, repeats: true)

确保使用其他变量声明声明计时器，以便在满足条件后它可以失效：

@objc
func loop() {
    if yourCondition {
        // your code here
        timer.invalidate()
    }
}

Answer 2

你可以像这样使用NSTimer

[NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(yourMethodName) userInfo:nil repeats:YES];

Answer 3

我刚刚整理了一个Swift NSObject扩展，允许你这样做。它使用延迟功能，允许您wait直到满足某些条件或取消它。

https://gist.github.com/d3signerd/795a9dced39cbee056010d5629d9ca06

//等待示例

waitWhile( { [weak self] () -> condition_parameters in

   if let weakSelf = self {
      return ( conditionMet: `criteria to meet`, cancel: false )
   }
   else {
      return ( conditionMet: false, cancel: true )
   }

 }, completion: { [weak self] in

    // Wait completion code goes here...

 })

//延迟示例

private var cancelableDelayClosure:dispatch_cancelable_closure? = nil

cancelableDelayClosure = delay( 1.0, closure: { () -> () in

    // Delay completion code here...
})

cancelDelay( &cancelableDelayClosure )

Answer 4

更新了swift的代码，

let timer = Timer.scheduledTimer(
                timeInterval: 1.0, target: self, selector: #selector(Your_current_vc.yourTask),
                userInfo: nil, repeats: true)


func yourTask() {

}

Answer 5

iOS 10

Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { (timer) in

    if someCondition {
        timer.invalidate()

    }
}

while循环在swift中每秒检查它的状态

5 个答案: