Xamarin直播间UIImageView

Question

我可以通过单击按钮将图片加载到UImageView，但不能从计时器加载。为什么会这样呢？我怎么才能修复它呢？

下面是我的代码：

void _timer_Elapsed(object sender, ElapsedEventArgs e)
{
    Patter_Function();
    switch_Function();
}



void switch_Function()
{

    image1 = new UIImage();
    image1 = UIImage.FromBundle("heart");

    image2 = new UIImage();
    image2 = UIImage.FromFile( @"White_Sharingan.png");

    image3 = new UIImage();
    image3 = UIImage.FromFile("snow.png");

    image4 = new UIImage();
    //image4.//FromFile("Images/waterfront.jpg");



        switch (Patter_1[switch_Counter].Move0) { 
        case 0 :
            Box_1.Image =  image1;
            break;
                case 1 :
                Box_1.Image = image1;
                break;
                case 2 :
                Box_2.Image = image1;
                break;
                case 3:
                Box_3.Image = image1;
                break;
                case 4:
                Box_4.Image = image1;
                break;
                case 5:
                Box_5.Image = image1;
                break;
                case 6:
                Box_6.Image = image1;
                break;
                case 7:
                Box_7.Image = image1;
                break;
                case 8:
                Box12.Image = image1;
                break;
                case 9:
                Box_9.Image = image1;
                break;
                case 10:
                Box_10.Image = image1;
                break;
                case 11:
                Box_11.Image = image1;
                break;
                case 12:
                Box8.Image = image1;
                break;
                case 13:
                Box_13.Image = image1;
                break;
                case 14:
                Box_14.Image = image1;
                break;
                case 15:
                Box_15.Image = image1;
                break;
                case 16:
                Box_16.Image = image1;
                break;
                case 17:
                Box_17.Image = image1;
                break;
                case 18:
                Box_18.Image = image1;
                break;
                case 19:
                Box_19.Image = image1;
                break;
                case 20:
                Box_20.Image = image1;
                break;}


        switch (Patter_1[switch_Counter].Move1)
        {
            case 0:
                Box_1.Image = image2;
                break;
            case 1:
                Box_2.Image = image2;
                break;
            case 2:
                Box_2.Image = image2;
                break;
            case 3:
                Box_3.Image = image2;
                break;
            case 4:
                Box_4.Image = image2;
                break;
            case 5:
                Box_5.Image = image2;
                break;
            case 6:
                Box_6.Image = image2;
                break;
            case 7:
                Box_7.Image = image2;
                break;
            case 8:
                Box12.Image = image2;
                break;
            case 9:
                Box_9.Image = image2;
                break;
            case 10:
                Box_10.Image = image2;
                break;
            case 11:
                Box_11.Image = image2;
                break;
            case 12:
                Box8.Image = image2;
                break;
            case 13:
                Box_13.Image = image2;
                break;
            case 14:
                Box_14.Image = image2;
                break;
            case 15:
                Box_15.Image = image2;
                break;
            case 16:
                Box_16.Image = image2;
                break;
            case 17:
                Box_17.Image = image2;
                break;
            case 18:
                Box_18.Image = image2;
                break;
            case 19:
                Box_19.Image = image2;
                break;
            case 20:
                Box_20.Image = image2;
                break;
        }

    switch (Patter_1[switch_Counter].Move2)
    {
        case 0:
            Box_1.Image = image3;
            break;
        case 1:
            Box_2.Image = image3;
            break;
        case 2:
            Box_2.Image = image3;
            break;
        case 3:
            Box_3.Image = image3;
            break;
        case 4:
            Box_4.Image = image3;
            break;
        case 5:
            Box_5.Image = image3;
            break;
        case 6:
            Box_6.Image = image3;
            break;
        case 7:
            Box_7.Image = image3;
            break;
        case 8:
            Box12.Image = image3;
            break;
        case 9:
            Box_9.Image = image3;
            break;
        case 10:
            Box_10.Image = image3;
            break;
        case 11:
            Box_11.Image = image3;
            break;
        case 12:
            Box8.Image = image3;
            break;
        case 13:
            Box_13.Image = image3;
            break;
        case 14:
            Box_14.Image = image3;
            break;
        case 15:
            Box_15.Image = image3;
            break;
        case 16:
            Box_16.Image = image3;
            break;
        case 17:
            Box_17.Image = image3;
            break;
        case 18:
            Box_18.Image = image3;
            break;
        case 19:
            Box_19.Image = image3;
            break;
        case 20:
            Box_20.Image = image3;
            break;
    }

    switch (Patter_1[switch_Counter].Move3)
    {
        case 0:
            Box_1.Image = image4;
            break;
        case 1:
            Box_2.Image = image4;
            break;
        case 2:
            Box_2.Image = image4;
            break;
        case 3:
            Box_3.Image = image4;
            break;
        case 4:
            Box_4.Image = image4;
            break;
        case 5:
            Box_5.Image = image4;
            break;
        case 6:
            Box_6.Image = image4;
            break;
        case 7:
            Box_7.Image = image4;
            break;
        case 8:
            Box12.Image = image4;
            break;
        case 9:
            Box_9.Image = image4;
            break;
        case 10:
            Box_10.Image = image4;
            break;
        case 11:
            Box_11.Image = image4;
            break;
        case 12:
            Box8.Image = image4;
            break;
        case 13:
            Box_13.Image = image4;
            break;
        case 14:
            Box_14.Image = image4;
            break;
        case 15:
            Box_15.Image = image4;
            break;
        case 16:
            Box_16.Image = image4;
            break;
        case 17:
            Box_17.Image = image4;
            break;
        case 18:
            Box_18.Image = image4;
            break;
        case 19:
            Box_19.Image = image4;
            break;
        case 20:
            Box_20.Image = image4;
            break;
    }

    switch_Counter++;
    if (switch_Counter >4  )
    {
        switch_Counter = 0;
    }
}

我使用了调试器，所以我知道代码已经到了最后一行，但是当它到达那里时，它什么也不做。调试器说: UIKit.UIKitThreadAccessException: UIKit Consistency error:你正在调用一个只能从UI线程调用的UIKit方法。

有什么原因吗？

Answer 1

在修改UI视图时涉及到的任何操作，都需要在UI/主线程下进行。所以把代码放在的lambda中：

InvokeOnMainThread ( () => {
    // manipulate UI controls
});