Swift字典

字典初始化

基本语法：

[key 1: value 1, key 2: value 2, key 3: value

3]

var   airports:    Dictionary<String,       String>    = ["TYO": "Tokyo", "DUB":"Dublin"]

字典追加元素

var   airports:    Dictionary<String,       String>    = ["TYO": "Tokyo", "DUB":"Dublin"] airports["LHR"] = "London"

println("The dictionary of airports contains

\(airports.count) items.")

字典删除元素

通过 removeValueForKey(key)方法删除

var airports: Dictionary<String, String> =

["TYO": "Tokyo", "DUB": "Dublin"]

if         let          removedValue                   =

airports.removeValueForKey("DUB") {

println("The removed airport's nameis \(removedValue).")

} else {

println("The airports dictionary doesnot contain a value forDUB.")

}

字典长度

使用 count 属性。

var   airports:    Dictionary<String,       String>    = ["TYO": "Tokyo", "DUB":"Dublin"]

println("The dictionary of airports contains

\(airports.count) items.")

字典遍历

1.遍历方法

var airports = ["TYO": "Tokyo", "DUB": "Dublin"]

for (airportCode,airportName) in airports {

println("\(airportCode): \(airportName)")

}

２.遍历键和值

for airportCode in airports.keys {

println("Airport code: \(airportCode)")

}

for airportName in airports.values {

println("Airport name: \(airportName)")

}

获得键或值的数组：

let airportCodes= Array(airports.keys)

// airportCodes is ["TYO", "LHR"]

let airportNames = Array(airports.values)

// airportNamesis ["Tokyo","London Heathrow"]

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