ios - 方法不能在 Switch 语句中使用？

Question

为什么我不能在 switch 语句中使用 sceneWithSize:？如果我在 switch case 之外创建我的新游戏场景的对象，它工作正常吗？但是我根据用户选择的 spriteNode 切换游戏场景。为什么会发生这种情况，是否有替代方法来完成我想做的事情？

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
      /* Called when a touch begins */
        UITouch *touch = [touches anyObject];
        CGPoint location = [touch locationInNode:self];
        SKNode *node = [self nodeAtPoint:location];
        NSLog(@"Level Selected: %@", node.name);
        int x = [node.name intValue];

        switch (x) {
            case 1:
                 // if I move this code outside the switch statement it works?
                LevelOne *newscene = [LevelOne sceneWithSize:self.size]; // here is where I get an expected expression error?
                 //[self.view presentScene:newscene transition:[SKTransition doorsOpenVerticalWithDuration:1]];
                break;

            default:
                break;
        }
    }

Answer 1

这不是因为方法调用，而是因为你不能用变量声明开始一个case。您必须将整个 block 用大括号括起来，如下所示:

switch (x) {
        case 1: {
             // if I move this code outside the switch statement it works?
            LevelOne *newscene = [LevelOne sceneWithSize:self.size]; // here is where I get an expected expression error?
             //[self.view presentScene:newscene transition:[SKTransition doorsOpenVerticalWithDuration:1]];
            break;
        }

        default:
            break;
    }