Swift教程之NSDictionary

//MARK:----------字典--------------/* 字典（key : value）*///如果类型信息已知，使用[:]声明空字典。let emptyDictionary1 = [:]let emptyDictionary2 = Dictionary<String, Float>()let emptyDictionary3 = [String: Float]()print(emptyDictionary2.count)//var airports: Dictionary<String, String> = ["TYO": "Tokyo", "DUB": "Dublin"]var airportsDic = ["TYO": "Tokyo", "DUB": "Dublin"]print(airportsDic["TYO"])//---------添加----------airportsDic["LHR"] = "London"print(airportsDic)//-------修改------airportsDic["LHR"] = "London Heathrow" // the value for "LHR" has been changed to "London Heathrowprint(airportsDic)//等价于//airports.updateValue("Dublin International", forKey: "DUB")//print(airports)//------------删除-----------airportsDic["LHR"] = nilprint(airportsDic)//等价于//airportsDic("DUB")//print(airportsDic)//---------查询----------print("字典元素个数为" + String(airportsDic.count))print("字典包含 \(airportsDic.count) 个元素.")print(airportsDic.startIndex)print(airportsDic.endIndex)//-------------遍历字典-----------for (key, Value) in airportsDic{    print("\(key): \(Value)")}for key in airportsDic.keys{    print("Airport code: \(key)")}for Value in airportsDic.values{    print("Airport name: \(Value)")}let airportKeys = Array(airportsDic.keys)     // airportCodes is ["TYO", "LHR"]let airportValues = Array(airportsDic.values)   // airportNames is ["Tokyo", "London Heathrow"]print(airportKeys)print(airportValues)