Swift学习笔记三（Dictionary 篇）

let dictionary = ["zhangsan": 7,"lisi": 8,"wangwu": 9]
 
for(key,value) in dictionary{
    print("name = \(key) , age = \(value)")
}
 
/**
 name = zhangsan , age = 7
 name = lisi , age = 8
 name = wangwu , age = 9
 */
 
 

let dictionary = ["zhangsan": 7,"lisi": 8,"wangwu": 9]
 
for key in dictionary.keys.sorted(){
    print("name = \(key),age = \(dictionary[key])")
}
 
/**
 name = lisi,age = Optional(8)
 name = wangwu,age = Optional(9)
 name = zhangsan,age = Optional(7)
 */
 

• 使用下标脚本语法给一个键赋值 nil 来从字典当中移除一个键值对。
• 使用 removeValue(forKey:)来从字典里移除键值对。这个方法移除键值对如果他们存在的
  话，并且返回移除的值，如果值不存在则返回 nil 。

4.3 合并两个字典

var dictionary = ["zhangsan": 7,"lisi": 8]
dictionary.merge(["zhangsan":17,"wangwu": 19]) {(current, _) in current}
print(dictionary)
 
dictionary.merge(["zhagnsan": 27,"niuliu": 30]) {(current, _) in current}
print(dictionary)
 
/**
 ["lisi": 8, "zhangsan": 7, "wangwu": 19]
 ["niuliu": 30, "zhagnsan": 27, "wangwu": 19, "lisi": 8, "zhangsan": 7]
 */