协程的简单用法

函数

按常用排序
WaitForSeconds
WaitForEndOfFrame
WaitForFixedUpdate
WaitForSecondsRealtime
WaitUnil
WaitWhile

//WaitUntil：当返回值为True时则继续执行后面的内容
StartCoroutine(WaitUntilFunc());
//WaitForSeconds：延迟几秒后执行，时间单位为Float
StartCoroutine(WaitForSecondsFunc());
//WaitForSeconds：延迟几秒后执行（不受缩放影响），时间单位为Float
StartCoroutine(WaitForSecondsRealtimeFunc());
//WaitWhile：当返回值为False时则继续执行后面的内容
StartCoroutine(WaitWhileFunc());
//WaitForEndOfFrame：当前帧结束前调用
StartCoroutine(WaitForEndOfFrameFunc());
//当开启的协程结束时调用
StartCoroutine(WaitForStartCoroutine());

IEnumerator WaitUntilFunc()
{
    Debug.Log("WaitUntilFunc Start~");
    //10帧后执行
    yield return new WaitUntil(() => _frame> 10);
    Debug.Log("WaitUntilFunc End~");
}
IEnumerator WaitForSecondsFunc()
{
    Debug.Log("WaitForSecondsFunc Start~");
    //延迟两秒后执行（时间受缩放影响）
    yield return new WaitForSeconds(2f);
    Debug.Log("WaitForSecondsFunc End~");
}

IEnumerator WaitForSecondsRealtimeFunc()
{
    Debug.Log("WaitForSecondsRealtimeFuncStart~");
    //延迟两秒后执行（时间不受缩放影响）
    yield return new WaitForSecondsRealtime(2f);
    Debug.Log("WaitForSecondsRealtimeFuncEnd~");
}

IEnumerator WaitWhileFunc()
{
    Debug.Log("WaitWhileFunc Start~");
    //10帧后执行
    yield return new WaitWhile(()=> !(_frame>10));
    Debug.Log("WaitWhileFunc End~");
}

IEnumerator WaitForEndOfFrameFunc()
{
    Debug.Log("WaitForEndOfFrameFunc Start~");
    //当前帧结束前后调用
    yield return new WaitForEndOfFrame();
    Debug.Log("WaitForEndOfFrameFunc End~");
}

IEnumerator WaitForAsyncOperation()
{
    Debug.Log("WaitForAsyncOperation Start~");
    //当场景加载完毕后调用
    AsyncOperation async = null; 
    //异步加载完场景时完后调用
    async = SceneManager.LoadSceneAsync("SampleScene");
    //异步加载完AB时调用
    async = AssetBundle.LoadFromFileAsync("Path");
    //异步加载完资源时调用
    async = Resources.LoadAsync("Path");
    //异步下载完后执行
    var request = UnityWebRequest.Get(new Uri("www.baidu.com"));
    async = request.SendWebRequest();
    yield return async;
    Debug.Log("WaitForAsyncOperation End~");
}

IEnumerator WaitForStartCoroutine()
{
    Debug.Log("WaitForStartCoroutine Start~");
    //当开启的协程结束时调用（不是被挂起时噢，而是完成了协程）
    yield return StartCoroutine(WaitForSecondsFunc());
    Debug.Log("WaitForStartCoroutine End~");
}

协程的执行顺序

官网更加详细点这里哟
执行顺序

FixedUpdate
yield WaitForFixedUpdate
Update
yield null
yield WaitForSeconds
yield WWW
yield StartCoroutine
LateUpdate
yield WaitForEndOfFrame

Yleid Return是什么

简述
yield return 用来判断协程内部是否挂起或继续执行的语句
支持类型

IEnumerator
CustomYieldInstruction
YieldInstruction
AsyncOperation

自定义一个迭代器

就不一一展示用法了，代码太长，需要自己去尝试

    private void Start()
    {
        StartCoroutine(TestCor());
    }
    IEnumerator TestCor()
    {
        Debug.Log("TestCor Start~");
        yield return new CustomIEnumerator();
        yield return new Custom2IEnumerator();
        yield return new Custom3IEnumerator();
        yield return new Custom4IEnumerator();
        Debug.Log("TestCor End~");
    }
}
//继承了这四个对象则可以被yield reutrn 这样可以自定义一些挂起函数
public class CustomIEnumerator : IEnumerator
{
    private int _index = -1;
    private string[] strName = {"Alan", "Kino", "Bruce"};
    
    /// <summary>
    /// 每帧被调用
    /// </summary>
    /// <returns></returns>
    public bool MoveNext()
    {
        _index++;
        Debug.Log("MoveNext：" + (_index > strName.Length).ToString());
        return false;
        return _index < strName.Length;
    }
    public void Reset()
    {
        Debug.Log("Reset");
        _index = 0;
    }
    public object Current {
        get
        {
            Debug.Log("获取当前对象：" + strName[_index]);
            return strName[_index];
        }
    }
}
public class Custom2IEnumerator : CustomYieldInstruction
{
    public override bool keepWaiting { get; }
}
public class Custom3IEnumerator : YieldInstruction
{
    
}
public class Custom4IEnumerator : AsyncOperation
{
    
}

优化

有些不需要每帧进行执行的任务可以使用协程延迟
官网案例

IEnumerator DoCheck() 
{
	//循环调用
    for(;;) 
    {
        ProximityCheck();
        //延迟0.1s后执行
        yield return new WaitForSeconds(.1f);
    }
}

缓存挂机函数

private WaitForSeconds delay = new WaitForSeconds(.1f);
IEnumerator TestCor() 
{
    //循环调用
    for(;;) 
    {
        //延迟0.1s后执行
        yield return delay;
    }
}