swift－for循环遍历,遍历字典,循环生成数组

// Playground - noun: a place where people can play

import UIKit

//------------------------------------------------------------------------------
// 1. for
// 传统的for循环方式在swift中相同支持
var num = 0
for(var i = 0; i < 10 ; i++) {
    num += i
}
num

//------------------------------------------------------------------------------
// 2. for-in用来遍历一个区间(range)、序列(sequence)、集合(collection)、系列(progression)
//    全部的元素运行一系列语句

// 1> 闭区间循环，从1循环到10
num = 0
for i in 1...10 {
    num += i
}
num

// 2> 开区间循环，从1循环到9
num = 0
for i in 1..<10 {
    num += i
}
num

// 3> 假设不须要知道区间内每一项的值，能够使用下划线(_)替代变量名。忽略对区间数值的訪问
num = 0
for _ in 1...10 {
    num++
}
num

num = 0
for i in 0...5 {
    for j in 0...5 {
        num = i + j
    }
}
num

//------------------------------------------------------------------------------
// 3. 循环生成数组
var array = [String]()
for i in 0..<10 {
    array.append("dylan \(i)")
}
array

//------------------------------------------------------------------------------
// 4. 循环遍历字典
var ageDict:Dictionary<String, Int> = ["mary": 19, "rose": 20]

var names = [String]()
var ages = [Int]()
for (key, value) in ageDict {
    names.append(key)
    ages.append(value)
}
names
ages

var keys = [String]()
var values = [String]()
var dict1 = ["name": "mike", "age": "18"];
for (name, age) in dict1 {
    keys.append(name)
    values.append(age)
}
keys
values

//------------------------------------------------------------------------------
// 5. 使用标签退出循环
// 使用标签的当中1个作用是：能够明白指定要退出哪个循环，下面演示样例是退出名字为"mainloop"的循环
var result = 1;
mainloop : for i in 1...5 {
    for j in 1...5 {
        result += j
        
        if (i == 3 && j == 3) {
            break mainloop
        }
    }
}
result