let numbers = [1,2,3,4]
let result = numbers.map { $0 + 2 }
let result2 = numbers.flatMap { $0 + 2 }
print(result,result2) // [3,4,5,6]
let numbersCompound = [[1,3],[4,6]];
let flatRes = numbersCompound.flatMap { $0.map{ $0} }
let filteredArray = flatRes.filter({$0 > 5}) 原文链接：https://www.f2er.com/swift/321103.html
