var demoDic = [Int : String]() // 为字典赋值 demoDic[12] = "hello,Dictinary"
@H_403_0@二、字典字面量 @H_403_0@字典字面量是用方括号方法将“值”括起来,不同“值”之间用逗号隔开,字典中的每个值是一个键值对组合。
字典字面量格式:[key1:value1,key2:value2,key3:value3]
示例:
var week : [String : String] = ["yesterday":"Sunday","today":"Monday","tomorrow":"Tuesday"] // 简化写法: var week = ["yesterday":"Sunday","tomorrow":"Tuesday"]
三、字典的一些使用 @H_403_0@1、通过count统计字典中键值对的个数 @H_403_0@
println("week中含有\(week.count)个元素") // 打印week数目为3@H_403_0@ @H_403_0@2、通过isEmpty判断字典是否为空
if week.isEmpty { println("week字典为空") }else{ println("week字典非空") }@H_403_0@ @H_403_0@3、字典增加长度:字典中可以通过附属脚本的语法来增加其长度,示例:dic[key] = value;在插入新的键值对时必须和字典中所存储的键值对类型相匹配
week["theDayBeforeYesterday"] = "Saturday" println("week字典数目\(week.count)") // 打印数目为4
@H_403_0@4、修改已有键值
week["today"] = "Mon" println("\(week)")@H_403_0@我们可以通过字典提供的updateValue(forKey:)方法来增添或者修改字典里的数据。需要指出的是:当使用updateValue(forKey:)方法为数组增加一个新的键值对时,该方法返回值为空,当用这个方法修改一个已存在键值对时,返回修改前的值。 @H_403_0@修改一个值
let oldValue = week.updateValue("Sun",forKey: "yesterday")@H_403_0@5、删除字典键值对
let removeValue = week.removeValueForKey("yesterday")四、字典遍历 @H_403_0@ @H_403_0@同数组一样,字典遍历也需要使用for in循环。不过和遍历数组有所不同,对于字典遍历可以遍历字典键值对,也可以遍历键或者值的集合。 @H_403_0@
// 1、遍历字典键值对 for (weekKey,weekValue) in week { println("\(weekKey) : \(weekValue)") } // 2、遍历字典所有的键 for weekKey in week.keys { println("\(weekKey)") } // 3、遍历字典所有值 for weekValue in week.values { println("\(weekValue)") }