/// Calls the given closure on each element in the sequence in the same order
/// as a `for`-`in` loop.
///
/// The two loops in the following example produce the same output:
///
/// let numberWords = ["one", "two", "three"]
/// for word in numberWords {
/// print(word)
/// }
/// // Prints "one"
/// // Prints "two"
/// // Prints "three"
///
/// numberWords.forEach { word in
/// print(word)
/// }
/// // Same as above
///
/// Using the `forEach` method is distinct from a `for`-`in` loop in two
/// important ways:
///
/// 1. You cannot use a `break` or `continue` statement to exit the current
/// call of the `body` closure or skip subsequent calls.
/// 2. Using the `return` statement in the `body` closure will exit only from
/// the current call to `body`, not from any outer scope, and won't skip
/// subsequent calls.
///
/// - Parameter body: A closure that takes an element of the sequence as a
/// parameter.
public func forEach(_ body: (Element) throws -> Void) rethrows
数组的 for each函数和 for in 循环的区别
forEach 不能调用continue,break
forEach 调用Return 退出当前闭包
