免责声明: swift noob
嗨,我刚刚开始学习Swift,并且正在学习Swift编程语言(苹果在WWDC期间发布的书),我想知道“where”关键字是什么。它被用于
let vegetable = "red pepper"
switch vegetable {
case "celery":
let vegetableComment = "Add some raisins and make ants on a log."
case "cucumber", "watercress":
let vegetableComment = "That would make a good tea sandwich."
case let x where x.hasSuffix("pepper"):
let vegetableComment = "Is it a spicy \(x)?"
default:
let vegetableComment = "Everything tastes good in soup."
}
摘自:苹果公司。“Swift编程语言。”iBooks。https://itun.es/us/jEUH0.l
如果有人能用另一种语言(java、c++、obj-c等)解释和/或展示等同内容。那太好了。
如果有人问过这个问题,很抱歉,我在任何地方都没有看到它。
发布于 2016-02-18 19:54:30
您可以在单个if语句中包含多个可选绑定,并使用where子句检查布尔条件:
if let firstNumber = Int("4"), secondNumber = Int("42") where firstNumber < secondNumber {
print("\(firstNumber) < \(secondNumber)")
}
// prints "4 < 42
https://stackoverflow.com/questions/25336079
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