Swift快速入门（八）

字典

字典的初始化

print("-------------字典的初始化-------------")

var dict1:Dictionary<String,Int> = ["a":1,"b":2,"c":3]//指定类型的键值对

print("dict1 = \(dict1)")

let dict2:[Int:String] = [1:"a",2:"b"]//指定类型的键值对

print("dict2 =\(dict2)")

var dict3 = ["key1":"A","key2":"B"]//类型推断

print("dict3 = \(dict3)")

let dict4:Dictionary<String,Int> = [String:Int]()//空字典

print("dict4 = \(dict4)")

let dict5 = [Int:String]()//空字典

print("dict5 = \(dict5)")

字典的过滤

let newDict = dict1.filter({(key,value) -> Bool in

  return key != "a"//过滤出来key != a的

})

print("过滤字典 = \(newDict)")

字典的遍历

for(key,value) in dict1{

  print("key = \(key),value =\(value)")

}


for key in dict1.keys {
    print("key : (key)")
}


for value in dict1.values {
    print("value : (value)")
}

字典的常用操作

print("-------------字典的常用操作-------------")

print("获取字典的长度 =\(dict3.count)")

dict1["a"] = 100

print("修改value =\(dict1)")

dict1.updateValue(200,forKey:"b")

print("修改value =\(dict1)")dict1.updateValue(400,forKey:"d")

print("修改value ,如果不存在就新增=\(dict1)")

dict1.removeValue(forKey:"c")

print("删除value = \(dict1)")