如何从Swift中的字典中获取键的值？

使用下标访问字典键的值。这将返回一个可选：

let apple: String? = companies["AAPL"]

要么

if let apple = companies["AAPL"] {    // ...}

您还可以枚举所有键和值：

var companies = ["AAPL" : "Apple Inc", "GOOG" : "Google Inc", "AMZN" : "Amazon.com, Inc", "FB" : "Facebook Inc"]for (key, value) in companies {    print("(key) -> (value)")}

或枚举所有值：

for value in Array(companies.values) {    print("(value)")}