About Swift
Before
以前 Objective-C 時:
#include <studio.h>
int main()
{
printf("Hello world!")
return 0;
}
Swift
現在的 Swift:
println("Hello world!")
Variable
宣告一個變數:
var languagnName: String = "Swift"
宣告一個 Constant 變數:
let languagnName: String = "Swift"
更多範例:
var version: Double = 1.0
var introduced: Int = 2014
var isAwesome: Bool = true
Type Inference (型態推論)
如果不寫 String
的話,Swift 也會自動幫你推論出變數型態:
let languagnName = "Swift" // 推論為 String
var version = 1.0 // 推論為 Double
var introduced = 2014 // 推論為 Int
var isAwesome = true // 推論為 Bool
Unicode Names
另外一個更酷的地方,可以使用 Unicode 當做變數名稱,像是 Ruby,也就是說,中文也可以啦!
let languagnName = "Swift"
var version: Double = 1.0
var introduced: Int = 2014
var isAwesome: Bool = true
let 馬英丸 = "bumbler"
println("馬英丸= \(馬英丸)")
輸出之後我們就會得到:
馬英丸= bumbler
真是太先進了!
String (字串)
Swift 的 String
也很強大 (總算不用寫 '@' 啦),例如:
let someString = "I appear to be a string"
// 會推論出此變數為 String
var isEmptyString = "Hello World".isEmpty
// 結果為 false
Character (字元)
而 String
是由 Character
所產生的,例如:
for character in "mouse"{
println(character)
}
輸出結果:
m
o
u
s
e
換成任何 unicode 都可以
for character in "蘋果好樣的"{
println(character)
}
輸出結果:
蘋
果
好
樣
的
Combining Strings and Characters (合併字串與字元)
字串與字元可以隨意的組合,例如:
let dog: Character = "狗"
let cow: Character = "牛"
let dogCow = dog + cow
// dogCow is "狗牛"
let instruction = "Beware of the" + dog
// instruction is "Beware of the 狗"
Building Complex String (建立複雜字串)
Swift 可以很快速的建立複雜的 String
let a = 3, b = 5
let mathResult = "\(a) times \(b) is \(a * b)"
// mathResult 為 "3 times 5 is 15"
String Mutability (字串變動)
String
也可以被操作,加減字串等,例如:
var variableString = "Horse"
variableString += " and carriage"
// varaibleString is now "Horse and carriage"
但是,也可以限制字串不能被操作、被修改,例如:
let constantString = "Highlander"
constantString += " and carriage"
// error - constantString can not be changed
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