Question

我有一个变量gameMode，我想在点击屏幕时在Vertical和Horizontal之间切换。我遇到的问题是它只需要较低的变量，gameMode总是显示为水平。我怎么能解决这个问题，以便在调用touchesBegan方法时切换它？任何帮助表示赞赏！

以下是我遇到问题的代码：

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {


    if gameMode == "Horizontal" {

        gameMode = "Vertical"

    }


    if gameMode == "Vertical" {

        gameMode = "Horizontal"

    }


    print(gameMode) }

Answer 1

会发生这种情况，因为如果gameMode为"Horizontal"，则您将gameMode设置为"Vertical"，此后gameMode == "Vertical"会返回true，因此您需要设置gameMode "Horizontal"至override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) { if gameMode == "Horizontal" { gameMode = "Vertical" } else { gameMode = "Horizontal" } print(gameMode) }。

试试这段代码：

enum

您应该使用enum GameMode { case horizontal case vertical mutating func toggle() { self = self == .horizontal ? .vertical : .horizontal } } var gameMode: GameMode = .horizontal override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) { gameMode.toggle() print(gameMode) }而不是字符串。

示例：

{{1}}

Answer 2

您可以使用三元运算符

切换这两种状态

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    gameMode = gameMode == "Horizontal" ? "Vertical" : "Horizontal"
    print(gameMode) 
}

对于只有两个状态，布尔变量可能更合适。如果gameMode为Bool，您只需撰写

即可

gameMode = !gameMode

Answer 3

我会替换

if gameMode == "Horizontal" {

    gameMode = "Vertical"

}


if gameMode == "Vertical" {

    gameMode = "Horizontal"

}

带

if gameMode == "Horizontal" {

    gameMode = "Vertical"

} else {

    gameMode = "Horizontal"

}

在一行中有两个 if 语句，当您将“Horizontal”作为值发送时，它会将其切换为“Vertical”。这也将使第二个声明启动并将其切换回来。使用if / else将确保它只运行一次。

切换swift时在两个变量之间来回切换的最佳方法

3 个答案: