Swift starts learning _02 from scratch

Swift the next day

A. Dictionary

The dictionary in Swift does not store arbitrary objects like OC, and the dictionary in Swift needs to define the type of stored key values in advance, can specify the type directly, or let him infer it himself.

The Dictionary of Swift uses theDictionary<KeyType, ValueType>方式来definition.

var dic = ["FirstName": "Chris", "LastName": "Paul"]//Create dictionary directly

var dic1:dictionary<string,string> = ["FirstName": "Chris", "LastName": "Paul"]//Create a dictionary while specifying the type of the key value, which is not prompted when the type is specified, Hard to hit.

dic["Team" = "LAC"//This allows you to add a key-value pair for the dictionary, and the same can be changed directly by the key to the corresponding value

var x = dic.updatevalue ("LAL", Forkey: "Team")//This method changes value by key, the return value is the previous value changed, if the corresponding key does not exist, will return nil, but the dictionary will add the key value pair

dic["Team"] = nil//can be removed from the dictionary by putting the key to nil

var x = Dic.removevalueforkey ("team")//key-value pairs are removed according to key, the same key error will return nil, here can not be received by X

println (Dic.keys)//Get all the keys, the same as in OC

var Keysarray = Array (dic.keys)//Remove all keys and construct an array, personal sense, if you want to receive in the desired format, need to build an object like this

var Testarray = dictionary<int,string> ()//Create an empty dictionary, specifying the type of key and value

TESTARRAY[3] = "Chris"//Add a key-value pair to an empty dictionary, you need to press the specified data type, or you will get an error

The Var object in Swift is mutable, and the Let object is immutable, that is, if you want to create an immutable array or dictionary, it can be modified to let, and the modification to Var is mutable (personal understanding)

Two. For loop

①. Traditional for loops are also available in Swift

for (var i = 0; i < 5; i++) {

println (i)///First of all, the first method is no different from the for loop used before

}

A cycle in the ②.swift

For I in 1...5{

println (i)//for. In, where 1 ... 5 is 1 to 5 meaning

}

③.let Power = 10

var answer = 1

For _ in 1...power {

answer++//This cycle, _ is to ignore the worth of access, just a simple loop, in this case is simply 10 cycles

}

④. Iterating through an array

var array = ["One", "both"]

For STR in array{//traversal array, str can be arbitrary

println (str)

}

⑤. Traversing a dictionary

var dictionary = ["FirstName": "Chris", "LastName": "Paul"]

for (Key,value) in dictionary{

println ("\ (key), \ (value)")//Traversal Dictionary

}

⑥. Traversing strings

For character in "Hello" {

println (character)//an intuitive here does not indicate that the type of the object being traversed is inappropriate, but it is estimated that this is Swift's grammatical habit, hoping to get used to it later.

}

Conclusion, today's swift learning so much, feel a bit accustomed to this grammar, in fact, compared to OC or a lot of simple, continue to insist!

Swift starts learning _02 from scratch