import UIKit

let words = "Blogging is about going through a memory stack of searching and storing knowledge, references, keyword indexing, and so on. Because my brain started like a memory stack, from empty stack to stack overflow, later use heap to store knowledge, found that memory is also OOM. Then I used reference tags to store iOS developing-related articles, tutorials, tricks, tricks, practice code, etc., which made my browser tabs look like they were poisoned. Later, I only remembered a few keywords to Google related articles. Sometimes some people post articles and delete them, so I can't find them. In addition, I have accumulated some skills and shared some skills. So I decided to blog about it. My skills are way, way out of line with yours truly. So I should write more and record the bit by bit of my growth process. Even though my views are filled with too many narrow theories and immature arguments, I must know that today is not yesterday. Otherwise I would have been sorry for wasting my time and ashamed for doing nothing."
let NON_WORDS = ["a", "of", "and", "!"]
func wordFrep(word: String) -> [String: Int] {
    var wordDict:[String: Int] = [:]
    let wordList = words.split(separator: " ");
    for word in wordList {
        let lowercaseWord = word.lowercased()
        if !NON_WORDS.contains(lowercaseWord) {
            if let count = wordDict[lowercaseWord] {
                wordDict[lowercaseWord] = count + 1
            } else {
                wordDict[lowercaseWord] = 1
            }
        }
    }
    return wordDict
}
print(wordFrep(word: words))

import UIKit

let words = "Blogging is about going through a memory stack of searching and storing knowledge, references, keyword indexing, and so on. Because my brain started like a memory stack, from empty stack to stack overflow, later use heap to store knowledge, found that memory is also OOM. Then I used reference tags to store iOS developing-related articles, tutorials, tricks, tricks, practice code, etc., which made my browser tabs look like they were poisoned. Later, I only remembered a few keywords to Google related articles. Sometimes some people post articles and delete them, so I can't find them. In addition, I have accumulated some skills and shared some skills. So I decided to blog about it. My skills are way, way out of line with yours truly. So I should write more and record the bit by bit of my growth process. Even though my views are filled with too many narrow theories and immature arguments, I must know that today is not yesterday. Otherwise I would have been sorry for wasting my time and ashamed for doing nothing."
let NON_WORDS = ["a", "of", "and", "!"]
func wordFrep2(words: String) -> [String: Int] {
    var wordDict: [String: Int] = [:]
    let wordList = words.split(separator: " ")
    wordList.map { $0.lowercased()}
            .filter{ !NON_WORDS.contains($0)}
            .forEach { wordDict[$0] = (wordDict[$0] ?? 0) + 1 }
    return wordDict
}
print(wordFrep2(words: words))

let source = "Hello world"
let target: [Character] = ["a","e","i","o","u"]
zip(0..<source.count, source).forEach { (index, char) in
   if target.contains(char) {
       print(index)
   }
}

let a = [1, 2, 3, 4, 5]
let b = ["a", "b", "c", "d"]
let c = zip(a, b).map { $0 }
print(c)
//输出 [(1, "a"), (2, "b"), (3, "c"), (4, "d")]

let b = ["a", "b", "c", "d"]
let c = zip(1..., b).map { $0 }
print(c)
//输出 [(1, "a"), (2, "b"), (3, "c"), (4, "d")]