ios - 从 viewWillLayoutSubviews 移动到 viewDidLoad 后 View 不显示

Question

我一直在尝试自学 Objective-C，但我在 View 方面遇到了一些问题。

将所有内容从 viewWillLayoutSubviews 移出后至viewDidLoad我的场景没有呈现出来。 MyScene.m 中的代码正在运行，我只是看不到它。我在这里遗漏了一些明显的缺陷吗？

上一个 viewWillLayoutSubviews方法如下。这里的所有内容都被直接切割成viewDidLoad不包括 [super viewDidLayoutSubviews] .

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];

    SKView * skView = (SKView *)self.view;
    if (!skView.scene) 
    {
        skView.showsFPS = YES;
        skView.showsNodeCount = YES;

        SKScene * scene = [MyScene sceneWithSize:skView.bounds.size];
        scene = [MyScene sceneWithSize:skView.bounds.size];
        scene.scaleMode = SKSceneScaleModeAspectFill;

        [skView presentScene:scene];
    }

    UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:(scene) action:@selector(screenSwipedRight)];
    swipeRight.numberOfTouchesRequired = 1;
    swipeRight.direction=UISwipeGestureRecognizerDirectionRight;
    [self.view addGestureRecognizer:(swipeRight)];

    UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:(scene) action:@selector(screenSwipedLeft)];
    swipeLeft.numberOfTouchesRequired = 1;
    swipeLeft.direction=UISwipeGestureRecognizerDirectionLeft;
    [self.view addGestureRecognizer:(swipeLeft)];

    UISwipeGestureRecognizer *swipeUp = [[UISwipeGestureRecognizer alloc] initWithTarget:(scene) action:@selector(screenSwipedUp)];
    swipeUp.numberOfTouchesRequired = 1;
    swipeUp.direction=UISwipeGestureRecognizerDirectionUp;
    [self.view addGestureRecognizer:(swipeUp)];

}

如果有帮助，我将所有内容从 viewWillLayoutSubviews 移出至viewDidLoad以避免每次 View 旋转时重新创建手势识别器。

谢谢你的帮助!

Answer 1

你为什么这么做？初始化 SKScene 的公认方法是 viewWillLayoutSubviews .

只需在 !skView.scene 中创建手势识别器即可堵塞:

if (!skView.scene) 
{
    // init everything here that should be initialized only once
    // AND should not re-run every time the view rotates
}

就这么简单。