Objective-C switch 语句的奇怪行为

Question

我有一款游戏使用全局整数 position 在选项菜单中导航。当为每个屏幕按下后退按钮时，它会调用一个函数 [self options]，以重新加载原始 "options" 屏幕。我有一种感觉，这是我搞砸的非常愚蠢的事情。

现在，调用判断是否返回按钮的函数的代码是这样的：

if ([self touchIsInNode:[self childNodeWithName:@"back"] touchPoint:touchPoint]) {
                    // stuff should happen here
                }

touchIsInNode: 是我自己的自定义方法，用于处理返回 BOOL 值的点击（如果是 YES）。

为每个屏幕的后退按钮命名按钮 backa、backb、backc 等是一个可行的解决方法，但它仍然会调用每个开关盒中的代码无论 position.

的值如何

这是我在 switch 声明中的内容：

switch (position) {
            // case 0 thru 3 are unrelated to the question... 0 is for the main menu, 1 is for the original logic for the "options" screen, 2 is for the end of the game, and 3 is to skip to the end of the intro screen.
            case 4:
            {
                NSLog(@"position: %i", position);
                if ([self touchIsInNode:[self childNodeWithName:@"backa"] touchPoint:touchPoint]) {
                    NSLog(@"store back button was pressed and [self options] is being called...");
                    [self options];
                }
                // store UI
            }
            case 5:
            {
                NSLog(@"position: %i", position);
                if ([self touchIsInNode:[self childNodeWithName:@"backb"] touchPoint:touchPoint]) {
                    NSLog(@"stats back button was pressed and [self options] is being called...");
                    [self options];
                }
                // stats UI
            }
            case 6:
            {
                NSLog(@"position: %i", position);
                if ([self touchIsInNode:[self childNodeWithName:@"backc"] touchPoint:touchPoint]) {
                    NSLog(@"about back button was pressed and [self options] is being called...");
                    [self options];
                }
                // about UI
            }
            case 7:
            {
                NSLog(@"position: %i", position);
                if ([self touchIsInNode:[self childNodeWithName:@"backe"] touchPoint:touchPoint]) {
                    NSLog(@"dev options back button was pressed and [self options] is being called...");
                    [self options];
                }
                // dev options UI
            }
            case 8:
            {
                NSLog(@"position: %i", position);
                if ([self touchIsInNode:[self childNodeWithName:@"backd"] touchPoint:touchPoint]) {
                    NSLog(@"purchased options back button was pressed and [self options] is being pressed...");
                    [self options];
                }
                // purchased options UI
            }
            default:
            {
                NSLog(@"INVALID POSITION: %i", position);
                break;
            }
        }
}

我的 options 方法如下所示：

for (SKNode* node in [self children]) {
    // fade out and remove each node if it is not "optionsButton"
    if (![node.name isEqual:@"optionsButton"]) {
        [node runAction:[SKAction fadeAlphaTo:0 duration:1] completion:^{
            [node removeFromParent];
        }];
    } else {
        // if it is "optionsButton", perform an animation.
        [node runAction:[SKAction scaleTo:1.5 duration:1]];
        [node runAction:[SKAction moveTo:CGPointMake(self.size.width / 2, self.size.height - ((node.frame.size.height * (4.0 / 3.0)) / node.yScale)) duration:1] completion:^{
            // afterwards, call a method that logs each node's name.
            [self logEveryNode];
        }];
    }
}
position = 1;
NSLog(@"position: %i", position);

// processing labels

// add in each child

NSLog(@"options called, with %i nodes in [self children]", [self children].count);

// fade in all of the labels

然后，对于选项菜单中的每个子菜单，它们看起来像这样（使用 "store" 作为模型）：

position = 4;
for (SKNode* node in [self children]) {
    if ([node.name isEqual:@"optionsButton"]) {
        [node runAction:[SKAction scaleTo:(2.0 / 3.0) duration:1]];
        [node runAction:[SKAction moveTo:CGPointMake(self.size.width / 2, self.size.height - (node.frame.size.height * (1.0 / 3.0))) duration:1]];
    } else if ([node.name isEqual:@"store"]) {
        [node runAction:[SKAction scaleTo:1.5 duration:1]];
        [node runAction:[SKAction moveTo:CGPointMake(self.size.width / 2, self.size.height - node.frame.size.height * 3) duration:1]];
    } else {
        [node runAction:[SKAction fadeAlphaTo:0 duration:1] completion:^{
            [node removeFromParent];
        }];
    }
}

// draw UI for the store and move the back button accordingly

SKLabelNode *back = [SKLabelNode labelNodeWithFontNamed:@"Cochin"];
back.alpha = 0;
back.fontColor = [UIColor blackColor];
back.text = @"back";
back.name = @"backa";
back.fontSize = 44;
back.position = CGPointMake(self.size.width / 2, self.size.height * 0.5);

[self addChild:back];

[back runAction:[SKAction fadeAlphaTo:1 duration:1]];

此代码的结果是，即使在 position 的值已更改为 1 以表示返回 options 菜单之后，每个案例都会执行。此外，didBeginTouches 被奇怪地调用了 5 次，尽管我在模拟器中只 "tapped" 屏幕一次。以下是我所拥有的日志中更相关的部分：

2015-05-23 01:10:40.581 game[25258:1981445] position: 4
2015-05-23 01:10:40.581 game[25258:1981445] store back button was pressed and [self options] is being called...
2015-05-23 01:10:40.582 game[25258:1981445] position: 1
2015-05-23 01:10:40.588 game[25258:1981445] options called, with 10 nodes in [self children]
2015-05-23 01:10:40.588 game[25258:1981445] position: 1
2015-05-23 01:10:40.588 game[25258:1981445] position: 1
2015-05-23 01:10:40.588 game[25258:1981445] position: 1
2015-05-23 01:10:40.589 game[25258:1981445] position: 1
2015-05-23 01:10:40.589 game[25258:1981445] INVALID POSITION: 1

为什么每个 case 运行，甚至是 default 案例？似乎只有 position == 4 应该运行 case 4 而类似 position == 500 的东西会运行 default 的情况。如果有帮助，选项菜单中有 5 个子菜单。

Answer 1

您需要在每个 case 块的末尾添加一个 break 语句。

Objective-C switch 语句的奇怪行为

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